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Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2017	Feb. 08, 2018	Jun. 30, 2017
Document and Entity Information
Entity Registrant Name	INCYTE CORP
Entity Central Index Key	0000879169
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 21.4
Entity Common Stock, Shares Outstanding		211,663,861
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 899,509	$ 652,343
Marketable securities-available-for-sale	270,136	156,203
Accounts receivable	266,299	148,758
Inventory	6,482	4,106
Prepaid expenses and other current assets	62,428	32,768
Total current assets	1,504,854	994,178
Restricted cash and investments	925	886
Long term investment	134,356	31,987
Inventory	7,966	15,193
Property and equipment, net	259,763	167,679
Other intangible assets, net	236,901	258,437
In-process research and development		12,000
Goodwill	155,593	155,593
Other assets, net	2,224	2,644
Total assets	2,302,582	1,638,597
Current liabilities:
Accounts payable	67,671	75,599
Accrued compensation	74,550	50,904
Interest payable	33	762
Accrued and other current liabilities	198,901	126,697
Acquisition-related contingent consideration	26,848	19,539
Convertible senior notes	7,393
Total current liabilities	375,396	273,501
Convertible senior notes	16,608	651,481
Acquisition-related contingent consideration	260,152	281,461
Other liabilities	19,797	12,687
Total liabilities	671,953	1,219,130
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; none issued or outstanding as of December 31, 2017 and December 31, 2016
Common stock, $0.001 par value; 400,000,000 shares authorized; 211,262,906 and 188,848,752 shares issued and outstanding as of December 31, 2017 and December 31, 2016, respectively	211	189
Additional paid-in capital	3,627,433	2,096,929
Accumulated other comprehensive loss	(7,010)	(2,886)
Accumulated deficit	(1,990,005)	(1,674,765)
Total stockholders' equity	1,630,629	419,467
Total liabilities and stockholders' equity	$ 2,302,582	$ 1,638,597

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
CONDENSED CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	211,262,906	188,848,752
Common stock, shares outstanding	211,262,906	188,848,752

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Product revenues, net	$ 1,200,312	$ 882,404	$ 601,015
Product royalty revenues	160,791	110,711	74,821
Milestone and contract revenues	175,000	112,512	77,857
Other revenues	113	92	58
Total revenues	1,536,216	1,105,719	753,751
Costs and expenses:
Cost of product revenues (including definite-lived intangible amortization)	79,479	58,187	26,972
Research and development	1,326,361	581,861	479,514
Selling, general and administrative	366,406	303,251	196,614
Change in fair value of acquisition-related contingent consideration	7,704	17,422
Total costs and expenses	1,779,950	960,721	703,100
Income (loss) from operations	(243,734)	144,998	50,651
Interest and other income, net	17,500	4,412	7,089
Interest expense	(6,900)	(38,745)	(45,603)
Unrealized loss on long term investments	(24,275)	(3,261)	(4,581)
Expense related to senior note conversions	(54,881)
Income (loss) before provision for income taxes	(312,290)	107,404	7,556
Provision for income taxes	852	3,182	1,025
Net income (loss)	$ (313,142)	$ 104,222	$ 6,531
Net income (loss) per share:
Basic	$ (1.53)	$ 0.55	$ 0.04
Diluted	$ (1.53)	$ 0.54	$ 0.03
Shares used in computing net income (loss) per share:
Basic	204,580,000	187,873,000	179,601,000
Diluted	204,580,000	194,125,000	187,302,000

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ (313,142)	$ 104,222	$ 6,531
Other comprehensive loss:
Foreign currency translation	(39)	(9)
Unrealized gain (loss) on marketable securities and long term investment, net of tax	1,615	504	(794)
Reclassification adjustment for realized (gain) loss on marketable securities		178	(1,830)
Defined benefit pension obligations, net of tax	(5,700)	(2,750)
Other comprehensive loss	(4,124)	(2,077)	(2,624)
Comprehensive income (loss)	$ (317,266)	$ 102,145	$ 3,907

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock [Member] 4.75% Convertible Senior Notes Due 2015	Common Stock [Member] Convertible Senior Notes 1.25 Percent Due 2020	Common Stock [Member] Convertible Senior Notes 0.375 Percent Due 2018	Common Stock [Member]	Additional Paid-in Capital [Member] 4.75% Convertible Senior Notes Due 2015	Additional Paid-in Capital [Member] Convertible Senior Notes 1.25 Percent Due 2020	Additional Paid-in Capital [Member] Convertible Senior Notes 0.375 Percent Due 2018	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	4.75% Convertible Senior Notes Due 2015	Convertible Senior Notes 1.25 Percent Due 2020	Convertible Senior Notes 0.375 Percent Due 2018	Total
Balances at Dec. 31, 2014				$ 171				$ 1,701,904	$ 1,815	$ (1,785,518)				$ (81,628)
Increase (Decrease) in Stockholders' Equity
Issuance of shares of Common Stock upon exercise of stock options and settlement of employee restricted stock units and shares of Common Stock under the ESPP				5				86,755						86,760
Issuance of shares of Common Stock upon conversion of Convertible Senior Notes	$ 11				$ 88,963	$ 180					$ 88,974	$ 180
Issuance of shares of Common Stock for services rendered								218						218
Excess tax provision from stock based compensation								2,872						2,872
Stock compensation expense								69,872						69,872
Other comprehensive loss									(2,624)					(2,624)
Net income (loss)										6,531				6,531
Balances at Dec. 31, 2015				187				1,950,764	(809)	(1,778,987)				171,155
Increase (Decrease) in Stockholders' Equity
Issuance of shares of Common Stock upon exercise of stock options and settlement of employee restricted stock units and shares of Common Stock under the ESPP				2				49,661						49,663
Issuance of shares of Common Stock upon conversion of Convertible Senior Notes					$ 4	5					$ 4	5
Issuance of shares of Common Stock for services rendered								294						294
Stock compensation expense								96,201						96,201
Other comprehensive loss									(2,077)					(2,077)
Net income (loss)										104,222				104,222
Balances at Dec. 31, 2016				189				2,096,929	(2,886)	(1,674,765)				419,467
Increase (Decrease) in Stockholders' Equity
Issuance of shares of Common Stock upon exercise of stock options and settlement of employee restricted stock units and shares of Common Stock under the ESPP				3				66,732						66,735
Issuance of shares of Common Stock upon conversion of Convertible Senior Notes		$ 7	$ 7			$ 330,004	$ 351,037					$ 330,011	$ 351,044
Issuance of shares of Common Stock for services rendered								294						294
Issuance of shares of Common Stock				5				649,382						649,387
Stock compensation expense								133,055						133,055
Other comprehensive loss									(4,124)					(4,124)
Adoption of accounting standard (Note 1)										(2,098)				(2,098)
Net income (loss)										(313,142)				(313,142)
Balances at Dec. 31, 2017				$ 211				$ 3,627,433	$ (7,010)	$ (1,990,005)				$ 1,630,629

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Issuance of shares of Common Stock upon exercise of stock options and restricted stock units	3,012,937	2,068,226	5,220,474
Issuance of shares of Common Stock under the ESPP	157,277	126,648	194,453
Issuance of shares of Common Stock for services rendered	2,532	3,438	2,017
Issuance of shares of Common Stock	4,945,000
4.75% Convertible Senior Notes Due 2015
Issuance of shares of Common Stock upon conversion of convertible senior notes			10,352,784
Convertible Senior Notes 1.25 Percent Due 2020
Issuance of shares of Common Stock upon conversion of convertible senior notes	7,095,350	77	3,902
Convertible Senior Notes 0.375 Percent Due 2018
Issuance of shares of Common Stock upon conversion of convertible senior notes	7,201,058	114

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ (313,142)	$ 104,222	$ 6,531
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Depreciation and amortization	52,178	58,425	44,883
In-process research and development impairment	12,000
Stock-based compensation	133,055	96,201	69,872
Expense related to senior note conversions	54,881
Other, net	290	472	(1,612)
Unrealized loss on long term investment	24,275	3,261	4,581
Change in fair value of acquisition-related contingent consideration	7,704	17,422
Changes in operating assets and liabilities:
Accounts receivable	(117,541)	(23,947)	(56,517)
Prepaid expenses and other assets	(31,367)	(13,069)	3,583
Inventory	4,851	4,047	98
Accounts payable	(7,928)	43,758	5,623
Accrued and other liabilities	87,756	26,476	25,245
Deferred revenue-collaborative agreements		(12,512)	(12,879)
Net cash (used in) provided by operating activities	(92,988)	304,756	89,408
Cash flows from investing activities:
Acquisition of business, net of cash acquired		(142,856)
Purchase of long term investments	(123,891)		(39,829)
Capital expenditures	(111,021)	(120,277)	(26,003)
Purchases of marketable securities	(260,780)	(57,372)	(108,152)
Sale and maturities of marketable securities	145,714	88,017	68,974
Net cash used in investing activities	(349,978)	(232,488)	(105,010)
Cash flows from financing activities:
Restricted investments, net	(39)	14,023	7
Proceeds from issuance of common stock under stock plans	66,764	49,973	86,436
Proceeds from issuance of common stock, net	649,387
Cash paid in connection with senior note conversions	(8,934)
Direct financing arrangements repayments		(445)	(1,699)
Payment of contingent consideration	(17,007)	(4,906)
Net cash provided by financing activities	690,171	58,645	84,744
Effect of exchange rates on cash and cash equivalents	(39)	(9)
Net increase in cash and cash equivalents	247,166	130,904	69,142
Cash and cash equivalents at beginning of period	652,343	521,439	452,297
Cash and cash equivalents at end of period	899,509	652,343	521,439
Supplemental Schedule of Cash Flow Information
Interest paid	314	7,218	12,746
Income taxes paid	6,305	927	62
Unpaid purchases of property and equipment	5,643	10,989
4.75% Convertible Senior Notes Due 2015
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversions or exchange of convertible senior notes			88,974
Convertible Senior Notes 0.375 Percent Due 2018
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Loss on repurchase of convertible senior notes	(1,400)
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversions or exchange of convertible senior notes	351,044	5
Convertible Senior Notes 1.25 Percent Due 2020
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Loss on repurchase of convertible senior notes	(5,100)
Supplemental Schedule of Cash Flow Information
Reclassification to common stock and additional paid in capital in connection with conversions or exchange of convertible senior notes	$ 330,011	$ 4	$ 180

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
4.75% Convertible Senior Notes Due 2015
Interest rate of debt (as a percent)			4.75%
Convertible Senior Notes 0.375 Percent Due 2018
Interest rate of debt (as a percent)	0.375%	0.375%
Convertible Senior Notes 1.25 Percent Due 2020
Interest rate of debt (as a percent)	1.25%	1.25%	1.25%

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization and Summary of Significant Accounting Policies
Organization and Summary of Significant Accounting Policies	Note 1. Organization and Summary of Significant Accounting Policies Organization and Business. Incyte Corporation (including its subsidiaries, “Incyte,” “we,” “us,” or “our”) is a biopharmaceutical company focused on developing and commercializing proprietary therapeutics. Our portfolio includes compounds in various stages, ranging from preclinical to late stage development, and commercialized products JAKAFI® (ruxolitinib) and ICLUSIG® (ponatinib). Our operations are treated as one operating segment. On June 1, 2016, we acquired (the “Acquisition”), pursuant to a Share Purchase Agreement dated as of May 9, 2016 (the “Share Purchase Agreement”), all of the outstanding shares of ARIAD Pharmaceuticals (Luxembourg) S.à.r.l., since renamed Incyte Biosciences Luxembourg S.à.r.l., the parent company of certain European subsidiaries of ARIAD Pharmaceuticals, Inc. (“ARIAD”). Refer to Note 2 for further information regarding the Acquisition. Principles of Consolidation. The consolidated financial statements include the accounts of Incyte Corporation and our wholly owned subsidiaries. All inter-company accounts, transactions, and profits have been eliminated in consolidation. Acquisitions. Acquired businesses are accounted for using the acquisition method of accounting, which requires that assets acquired and liabilities assumed be recorded at fair value, with limited exceptions. Any excess of the purchase price over the fair value of the net assets acquired is recorded as goodwill. Transaction costs are expensed as incurred. The operating results of the acquired business are reflected in our consolidated financial statements after the date of acquisition. Acquired in-process research and development (“IPR&D”) is recognized at fair value and initially characterized as an indefinite-lived intangible asset, irrespective of whether the acquired IPR&D has an alternative future use. Foreign Currency Translation. Operations in non-U.S. entities are recorded in the functional currency of each entity. For financial reporting purposes, the functional currency of an entity is determined by a review of the source of an entity's most predominant cash flows. The results of operations for any non-U.S. dollar functional currency entities are translated from functional currencies into U.S. dollars using the average currency rate during each month. Assets and liabilities are translated using currency rates at the end of the period. Adjustments resulting from translating the financial statements of our foreign entities that use their local currency as the functional currency into U.S. dollars are reflected as a component of other comprehensive income (loss). Transaction gains and losses are recorded in interest and other income, net, in the consolidated statements of operations. To date, both the translation gains or losses in other comprehensive income (loss) and the transaction gains or losses in foreign exchange gain (loss) have been immaterial. Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Concentrations of Credit Risk. Cash, cash equivalents, marketable securities, trade receivables and restricted investments are financial instruments which potentially subject us to concentrations of credit risk. The estimated fair value of financial instruments approximates the carrying value based on available market information. We primarily invest our excess available funds in debt securities and, by policy, limit the amount of credit exposure to any one issuer and to any one type of investment, other than securities issued or guaranteed by the U.S. government and money market funds that meet certain guidelines. Our receivables mainly relate to our product sales of JAKAFI, ICLUSIG and collaborative agreements with pharmaceutical companies. We have not experienced any significant credit losses on cash, cash equivalents, marketable securities, trade receivables or restricted investments to date and do not require collateral on receivables. Cash and Cash Equivalents. Cash and cash equivalents are held in banks or in custodial accounts with banks. Cash equivalents are defined as all liquid investments and money market funds with maturity from date of purchase of 90 days or less that are readily convertible into cash. Marketable Securities—Available‑for‑Sale. Available‑for‑sale securities are carried at fair value, based on quoted market prices and observable inputs, with unrealized gains and losses, net of tax, reported as a separate component of stockholders’ equity. We classify marketable securities that are available for use in current operations as current assets on the consolidated balance sheets. Realized gains and losses and declines in value judged to be other than temporary for available‑for‑sale securities are included in “Interest and other income, net.” The cost of securities sold is based on the specific identification method. Accounts Receivable. As of December 31, 2017 and 2016, we had no allowance for doubtful accounts. We provide an allowance for doubtful accounts based on experience and specifically identified risks. Accounts receivable are carried at fair value and charged off against the allowance for doubtful accounts when we determine that recovery is unlikely and we cease collection efforts. Inventory. Inventories are determined at the lower of cost and net realizable value with cost determined under the specific identification method and may consist of raw materials, work in process and finished goods. JAKAFI raw materials and work‑in‑process inventory is not subject to expiration and the shelf life of finished goods inventory is 36 months from the start of manufacturing of the finished goods. ICLUSIG raw materials and work-in-process inventory is not subject to expiration and finished goods inventory has a shelf life of 24 months from the start of manufacturing of the finished goods. We evaluate for potential excess inventory by analyzing current and future product demand relative to the remaining product shelf life. We build demand forecasts by considering factors such as, but not limited to, overall market potential, market share, market acceptance and patient usage. We classify inventory as current on the consolidated balance sheets when we expect inventory to be consumed for commercial use within the next twelve months. The ICLUSIG inventories were recorded at fair value less costs to sell in connection with the Acquisition, which resulted in a higher cost of ICLUSIG product revenues over a one year period from the acquisition date. Variable Interest Entities. We perform an initial and ongoing evaluation of the entities with which we have variable interests, such as equity ownership, in order to identify entities (i) that do not have sufficient equity investment at risk to permit the entity to finance its activities without additional subordinated financial support or (ii) in which the equity investors lack an essential characteristic of a controlling financial interest as variable interest entities (“VIE” or “VIEs”). If an entity is identified as a VIE, we perform an assessment to determine whether we have both (i) the power to direct activities that most significantly impact the VIE’s economic performance and (ii) have the obligation to absorb losses from or the right to receive benefits of the VIE that could potentially be significant to the VIE. If both of these criteria are satisfied, we are identified as the primary beneficiary of the VIE. As of December 31, 2017, there were no entities in which we held a variable interest which we determined to be VIEs. Long Term Investments. Our long term investments consist of investments in common stock of publicly held companies with whom we have entered into collaboration and license agreements. The investments in companies over which we have significant influence, but not controlling interest, are accounted for using the equity method (fair value option). The investments in companies over which we do not have significant influence are accounted for as available-for-sale securities. We classify all of our investments in common stock of publicly held companies with whom we have entered into collaboration and license agreements as long term investments. Equity Method Investments. In circumstances where we have the ability to exercise significant influence over the operating and financial policies of a company in which we have an investment, the investment is accounted for either (i) under the equity method of accounting or (ii) at fair value by electing the fair value option under U.S. GAAP. In assessing whether we exercise significant influence, we consider the nature and magnitude of our investment, any voting and protective rights we hold, any participation in the governance of the other company, and other relevant factors such as the presence of a collaboration or other business relationship. Under the equity method of accounting, we record within our results of operations our share of income or loss of the investee company. Under the fair value option, our investment is carried at fair value on our consolidated balance sheets as a long term investment and all changes in fair value are reported in our consolidated statements of operations as an unrealized gain (loss) on long term investments. Property and Equipment. Property and equipment is stated at cost, less accumulated depreciation and amortization. Depreciation is recorded using the straight‑line method over the estimated useful lives of the respective assets. Leasehold improvements are amortized over the shorter of the estimated useful life of the assets or lease term. Management continually reviews the estimated useful lives of technologically sensitive equipment and believes that those estimates appropriately reflect the current useful life of our assets. In the event that a currently unknown significantly advanced technology became commercially available, we would re‑evaluate the value and estimated useful lives of our existing equipment, possibly having a material impact on the financial statements. Lease Accounting. We account for operating leases by recording rent expense on a straight‑line basis over the expected life of the lease, commencing on the date we gain possession of leased property. We include tenant improvement allowances and rent holidays received from landlords and the effect of any rent escalation clauses to determine the straight‑line rent expense over the expected life of the lease. Capital leases are reflected as a liability at the inception of the lease based on the present value of the minimum lease payments or, if lower, the fair value of the property. Assets under capital leases are recorded in property and equipment, net on the consolidated balance sheets and depreciated in a manner similar to other property and equipment. Other Intangible Assets, net. Other intangible assets, net consist of licensed intellectual property rights acquired in business combinations, which are reported at fair value, less accumulated amortization. Intangible assets with finite lives are amortized over their estimated useful lives using the straight-line method. In-Process Research and Development. The fair value of in-process research and development (“IPR&D”) acquired through business combinations is capitalized as an indefinite-lived intangible asset until the completion or abandonment of the related research and development activities. When the related research and development is completed, the asset will be assigned a useful life and amortized. Impairment of Long-Lived Assets. Long-lived assets with finite lives are tested for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If indicators of impairment are present, the asset is tested for recoverability by comparing the carrying value of the asset to the related estimated undiscounted future cash flows expected to be derived from the asset. If the expected cash flows are less than the carrying value of the asset, then the asset is considered to be impaired and its carrying value is written down to fair value, based on the related estimated discounted future cash flows. Indefinite-lived intangible assets, including IPR&D, are tested for impairment annually as of October 1 or more frequently if events or changes in circumstances between annual tests indicate that the asset may be impaired. Impairment losses on indefinite-lived intangible assets are recognized based solely on a comparison of the fair value of the asset to its carrying value. Due to the discontinuation of the OPTIC-2L study described in Note 2 below, we considered our indefinite-lived IPR&D asset to be impaired and recorded a $12.0 million impairment charge in research and development expense on the consolidated statements of operations during the third quarter of 2017. Goodwill. Goodwill is calculated as the difference between the acquisition date fair value of the consideration transferred and the values assigned to the assets acquired and liabilities assumed. Goodwill is not amortized but is tested for impairment at the reporting unit level at least annually as of October 1 or when a triggering event occurs that could indicate a potential impairment by assessing qualitative factors or performing a quantitative analysis in determining whether it is more likely than not that the fair value of net assets are below their carrying amounts. A reporting unit is the same as, or one level below, an operating segment. Our operations are currently comprised of a single, entity wide reporting unit. We completed our most recent annual impairment assessment as of October 1, 2017 and determined that the carrying value of our reporting unit was not impaired. Income Taxes. We account for income taxes using the asset and liability approach which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and amounts reportable for income tax purposes. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more-likely-than-not that some portion or all of the deferred tax assets will not be realized. In addition, we follow the guidance related to accounting for uncertainty in income taxes. This guidance creates a single model to address uncertainty in tax positions and clarifies the accounting for income taxes by prescribing the minimum recognition threshold a tax position is required to meet before it is recognized in the financial statements. Financing Costs Related to Long‑term Debt. Costs associated with obtaining long‑term debt are deferred and amortized over the term of the related debt using the effective interest method. Such costs are presented as a direct deduction from the carrying amount of the long-term debt liability, consistent with debt discounts, on the consolidated balance sheets. Grant Accounting. Grant amounts received from government agencies for operations are deferred and are amortized into income over the service period of the grant. Grant amounts received for purchases of capital assets are deferred and amortized into interest and other income, net over the useful life of the related capital assets. Such amounts are recorded in other liabilities on the consolidated balance sheets. Net Income (Loss) Per Share. Our basic and diluted net income (loss) per share is calculated by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during all periods presented. Options to purchase stock, restricted stock units and shares issuable upon the conversion of convertible debt are included in diluted earnings per share calculations, unless the effects are anti‑dilutive. Accumulated Other Comprehensive Income (Loss). Accumulated other comprehensive income (loss) consists of realized and unrealized gains or losses on marketable securities that are classified as available-for-sale, a long-term investment classified as available-for-sale, foreign currency translation gains or losses and defined benefit pension obligations. Revenue Recognition. Revenues are recognized when (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the price is fixed or determinable and (4) collectability is reasonably assured. Revenues are deferred for fees received before earned or until no further obligations exist. We exercise judgment in determining that collectability is reasonably assured or that services have been delivered in accordance with the arrangement. We assess whether the fee is fixed or determinable based on the payment terms associated with the transaction and whether the sales price is subject to refund or adjustment. We assess collectability based primarily on the customer’s payment history and on the creditworthiness of the customer. Product Revenues Our product revenues consist of U.S. sales of JAKAFI and European sales of ICLUSIG. Product revenues are recognized once we meet all four revenue recognition criteria described above. In November 2011, we began shipping JAKAFI to our customers in the U.S., which include specialty pharmacies and wholesalers. In June 2016, we acquired the right to and began shipping ICLUSIG to our customers in the European Union and certain other jurisdictions (Note 2), which include retail pharmacies, hospital pharmacies and distributors. We recognize revenues for product received by our customers net of allowances for customer credits, including estimated rebates, chargebacks, discounts, returns, distribution service fees, patient assistance programs, and government rebates, such as Medicare Part D coverage gap reimbursements in the U.S. Product shipping and handling costs are included in cost of product revenues. Customer Credits: Our customers are offered various forms of consideration, including allowances, service fees and prompt payment discounts. We expect our customers will earn prompt payment discounts and, therefore, we deduct the full amount of these discounts from total product sales when revenues are recognized. Service fees are also deducted from total product sales as they are earned. Rebates and Discounts: Allowances for rebates include mandated discounts under the Medicaid Drug Rebate Program in the U.S. and mandated discounts in Europe in markets where government-sponsored healthcare systems are the primary payers for healthcare. Rebates are amounts owed after the final dispensing of the product to a benefit plan participant and are based upon contractual agreements or legal requirements with public sector benefit providers. The accrual for rebates is based on statutory discount rates and expected utilization as well as historical data we have accumulated since product launches. Our estimates for expected utilization of rebates are based on data received from our customers. Rebates are generally invoiced and paid in arrears so that the accrual balance consists of an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarters’ unpaid rebates. If actual future rebates vary from estimates, we may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Chargebacks: Chargebacks are discounts that occur when certain contracted customers, which currently consist primarily of group purchasing organizations, Public Health Service institutions, non‑profit clinics, and Federal government entities purchasing via the Federal Supply Schedule, purchase directly from our wholesalers. Contracted customers generally purchase the product at a discounted price. The wholesalers, in turn, charges back to us the difference between the price initially paid by the wholesalers and the discounted price paid by the contracted customers. In addition to actual chargebacks received we maintain an accrual for chargebacks based on the estimated contractual discounts on the inventory levels on hand in our distribution channel. If actual future chargebacks vary from these estimates, we may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Medicare Part D Coverage Gap: Medicare Part D prescription drug benefit mandates manufacturers to fund 50% of the Medicare Part D insurance coverage gap for prescription drugs sold to eligible patients. Our estimates for the expected Medicare Part D coverage gap are based on historical invoices received and in part from data received from our customers. Funding of the coverage gap is generally invoiced and paid in arrears so that the accrual balance consists of an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarters. If actual future funding varies from estimates, we may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Co‑payment Assistance: Patients who have commercial insurance and meet certain eligibility requirements may receive co‑payment assistance. We accrue a liability for co‑payment assistance based on actual program participation and estimates of program redemption using data provided by third‑party administrators. Product Royalty Revenues Royalty revenues on commercial sales for ruxolitinib (marketed as JAKAVI® outside the United States) by Novartis Pharmaceutical International Ltd. (“Novartis”) are based on net sales of licensed products in licensed territories as provided by Novartis. Royalty revenues on commercial sales for baricitinib (marketed as OLUMIANT) by Eli Lilly and Company (“Lilly”) are based on net sales of licensed products in licensed territories as provided by Lilly. We recognize royalty revenues in the period the sales occur. Cost of Product Revenues Cost of product revenues includes all JAKAFI related product costs as well as ICLUSIG related product costs. The acquired ICLUSIG inventories were recorded at fair value less costs to sell in connection with the Acquisition, and will result in a higher cost of ICLUSIG product revenues over the period in which this inventory is sold, which is expected to be over a one year period from the acquisition date. In addition, cost of product revenues include low single-digit royalties under our collaboration and license agreement to Novartis on all future sales of JAKAFI in the United States. Subsequent to the Acquisition on June 1, 2016, cost of product revenues also includes the amortization of our licensed intellectual property for ICLUSIG using the straight-line method over the estimated useful life of 12.5 years. Contract and License Revenues Under agreements involving multiple deliverables, services and/or rights to use assets that we entered into prior to January 1, 2011, the multiple elements are divided into separate units of accounting when certain criteria are met, including whether the delivered items have stand‑alone value to the customer and whether there is objective and reliable evidence of the fair value of the undelivered items. When separate units of accounting exist, consideration is allocated among the separate elements based on their respective fair values. The determination of fair value of each element is based on objective evidence from historical sales of the individual elements by us to other customers. If such evidence of fair value for each undelivered element of the arrangement does not exist, all revenue from the arrangement is deferred until such time that evidence of fair value for each undelivered element does exist or until all elements of the arrangement are delivered. When elements are specifically tied to a separate earnings process, revenue is recognized when the specific performance obligation tied to the element is completed. When revenues for an element are not specifically tied to a separate earnings process, they are recognized ratably over the term of the agreement. We assess whether a substantive milestone exists at the inception of our agreements. For all milestones within our arrangements that are considered substantive, we recognize revenue upon the achievement of the associated milestone. If a milestone is not considered substantive, we would recognize the applicable milestone payment over the remaining period of performance under the arrangement. As of December 31, 2017, all remaining potential milestones under our collaborative arrangements are considered substantive. On January 1, 2011, updated guidance on the recognition of revenues for agreements with multiple deliverables became effective and applies to any agreements we may enter into on or after January 1, 2011. This updated guidance (i) relates to whether multiple deliverables exist, how the deliverables in a revenue arrangement should be separated and how the consideration should be allocated; (ii) requires companies to allocate revenues in an arrangement using estimated selling prices of deliverables if a vendor does not have vendor‑specific objective evidence or third‑party evidence of selling price; and (iii) eliminates the use of the residual method and requires companies to allocate revenues using the relative selling price method. During the years ended December 31, 2017, 2016 and 2015, we did not enter into any agreements that are subject to this updated guidance. If we enter into an agreement with multiple deliverables after January 1, 2011 or amend existing agreements, this updated guidance could have a material effect on our financial statements. Our collaborations often include contractual milestones, which typically relate to the achievement of pre‑specified development, regulatory and commercialization events. These three categories of milestone events reflect the three stages of the life‑cycle of our drugs, which we describe in more detail in the following paragraphs. The regulatory review and approval process, which includes preclinical testing and clinical trials of each drug candidate, is lengthy, expensive and uncertain. Securing approval by the U.S. Food and Drug Administration (the “FDA”) requires the submission of extensive preclinical and clinical data and supporting information to the FDA for each indication to establish a drug candidate’s safety and efficacy. The approval process takes many years, requires the expenditure of substantial resources, involves post‑marketing surveillance and may involve ongoing requirements for post‑marketing studies. Before commencing clinical investigations of a drug candidate in humans, we must submit an Investigational New Drug application (“IND”), which must be reviewed by the FDA. The steps generally required before a drug may be marketed in the United States include preclinical laboratory tests, animal studies and formulation studies, submission to the FDA of an IND for human clinical testing, performance of adequate and well‑controlled clinical trials in three phases, as described below, to establish the safety and efficacy of the drug for each indication, submission of a new drug application (“NDA”) or biologics license application (“BLA”) to the FDA for review and FDA approval of the NDA or BLA. Similar requirements exist within foreign regulatory agencies as well. The time required satisfying the FDA requirements or similar requirements of foreign regulatory agencies may vary substantially based on the type, complexity and novelty of the product or the targeted disease. Preclinical testing includes laboratory evaluation of product pharmacology, drug metabolism, and toxicity, which includes animal studies, to assess potential safety and efficacy as well as product chemistry, stability, formulation, development, and testing. The results of the preclinical tests, together with manufacturing information and analytical data, are submitted to the FDA as part of an IND. The FDA may raise safety concerns or questions about the conduct of the clinical trials included in the IND, and any of these concerns or questions must be resolved before clinical trials can proceed. We cannot be sure that submission of an IND will result in the FDA allowing clinical trials to commence. Clinical trials involve the administration of the investigational drug or the marketed drug to human subjects under the supervision of qualified investigators and in accordance with good clinical practices regulations covering the protection of human subjects. Clinical trials typically are conducted in three sequential phases, but the phases may overlap or be combined. Phase I usually involves the initial introduction of the investigational drug into healthy volunteers to evaluate its safety, dosage tolerance, absorption, metabolism, distribution and excretion. Phase II usually involves clinical trials in a limited patient population to evaluate dosage tolerance and optimal dosage, identify possible adverse effects and safety risks, and evaluate and gain preliminary evidence of the efficacy of the drug for specific indications. Phase III clinical trials usually further evaluate clinical efficacy and safety by testing the drug in its final form in an expanded patient population, providing statistical evidence of efficacy and safety, and providing an adequate basis for labeling. We cannot guarantee that Phase I, Phase II or Phase III testing will be completed successfully within any specified period of time, if at all. Furthermore, we, the institutional review board for a trial, or the FDA may suspend clinical trials at any time on various grounds, including a finding that the subjects or patients are being exposed to an unacceptable health risk. Generally, the milestone events contained in our collaboration agreements coincide with the progression of our drugs from development, to regulatory approval and then to commercialization. The process of successfully discovering a new development candidate, having it approved and successfully commercialized is highly uncertain. As such, the milestone payments we may earn from our partners involve a significant degree of risk to achieve. Therefore, as a drug candidate progresses through the stages of its life‑cycle, the value of the drug candidate generally increases. Research and Development Costs. Our policy is to expense research and development costs as incurred. We often contract with clinical research organizations (“CROs”) to facilitate, coordinate and perform agreed upon research and development of a new drug. To ensure that research and development costs are expensed as incurred, we record monthly accruals for clinical trials and preclinical testing costs based on the work performed under the contract. These CRO contracts typically call for the payment of fees for services at the initiation of the contract and/or upon the achievement of certain clinical trial milestones. In the event that we prepay CRO fees, we record the prepayment as a prepaid asset and amortize the asset into research and development expense over the period of time the contracted research and development services are performed. Most professional fees, including project and clinical management, data management, monitoring, and medical writing fees are incurred throughout the contract period. These professional fees are expensed based on their percentage of completion at a particular date. Our CRO contracts generally include pass through fees. Pass through fees include, but are not limited to, regulatory expenses, investigator fees, travel costs, and other miscellaneous costs, including shipping and printing fees. We expense the costs of pass through fees under our CRO contracts as they are incurred, based on the best information available to us at the time. The estimates of the pass through fees incurred are based on the amount of work completed for the clinical trial and are monitored through correspondence with the CROs, internal reviews and a review of contractual terms. The factors utilized to derive the estimates include the number of patients enrolled, duration of the clinical trial, estimated patient attrition, screening rate and length of the dosing regimen. CRO fees incurred to set up the clinical trial are expensed during the setup period. Under our clinical trial collaboration agreements we may be reimbursed for certain development costs incurred. Such costs are recorded as a reduction of research and development expense in the period in which the related expense is incurred. Stock Compensation. Share-based payment transactions with employees, which include stock options, restricted stock units (“RSUs”) and performance shares (“PSUs”), are recognized as compensation expense over the requisite service period based on their estimated fair values as well as expected forfeiture rates. The stock compensation process requires significant judgment and the use of estimates, particularly surrounding Black-Scholes assumptions such as stock price volatility over the option term and expected option lives, as well as expected forfeiture rates and the probability of PSUs vesting. The fair value of stock options, which are subject to graded vesting, are recognized as compensation expense over the requisite service period using the accelerated attribution method. The fair value of RSUs that are subject to cliff vesting are recognized as compensation expense over the requisite service period using the straight-line attribution method, and the fair value of RSUs that are subject to graded vesting are recognized as compensation expense over the requisite service period using the accelerated attribution method. The fair value of PSUs are recognized as compensation expense beginning at the time in which the performance conditions are deemed probable of achievement, over the remaining requisite service period. We recorded $133.1 million, $96.2 million and $69.9 million of stock compensation expense for the years ended December 31, 2017, 2016 and 2015, respectively. Acquisition-Related Contingent Consideration. Acquisition-related contingent consideration, which consists of our future royalty and certain potential milestone obligations to ARIAD, is recorded on the acquisition date at the estimated fair value of the obligation, in accordance with the acquisition method of accounting. The fair value measurement is based on significant inputs that are unobservable in the market and thus represents a Level 3 measurement. The fair value of the acquisition-related contingent consideration is remeasured each reporting period, with changes in fair value recorded in the consolidated statements of operations. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers,” which will replace numerous requirements in U.S. GAAP, including industry-specific requirements. This guidance provides a five step model to be applied to all contracts with customers, with an underlying principle that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. ASU No. 2014-09 requires extensive quantitative and qualitative disclosures covering the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including disclosures on significant judgments made when applying the guidance. This guidance is effective for annual reporting periods beginning after December 15, 2017 and interim periods therein. We performed an impact assessment which consisted of a review of a representative sample of contracts, discussions with key stakeholders, and a cataloging of potential impacts on our financial statements, accounting policies, financial controls, and operations. The guidance will not have a material impact on our revenue recognition practices for product and royalty revenues. The adoption of ASU 2014-09 will have primarily two impacts on our future milestone and contract revenues generated by our collaborative research and license agreements: (i)Changes in the model for distinct licenses of functional intellectual property which may result in a timing difference of revenue recognition. Whereas revenue from these arrangements was previously recognized over a period of time pursuant to revenue recognition guidance that was in place for our arrangements at the time such arrangements commenced, revenue from new arrangements we enter into may now be recognized at a point in time under the new guidance. (ii)Assessments of milestone payments, which are linked to events that are in our control, will result in variable consideration that may be recognized at an earlier point in time under the new guidance, when it is probable that the milestone will be achieved without a significant future reversal of cumulative revenue expected. We completed our assessment of the impact of this guidance with the cumulative effect of initially applying the standard to be recognized at the date of initial application in retained earnings (also referred to as a “modified retrospective” adoption methodology). The impact under this methodology to our previously reported revenues is insignificant in the periods reported, with no effect to reported revenues in the fiscal year ended December 31, 2017. We will adopt the new standard effective for the fiscal period beginning January 1, 2018, and will report new disclosures required by this guidance within our Form 10-Q for the interim period ending March 31, 2018. Although the adoption of this new standard is anticipated to have an immaterial impact on our revenues and net income on an ongoing basis, we have implemented a controls process to identify and evaluate new revenue-generating contracts with third-party customers. We continue to monitor additional changes, modifications, clarifications or interpretations being undertaken by the FASB, which may impact our current conclusions. The standard will not impact assets or liabilities reported in our consolidated balance sheet; revenues or expenses within the consolidated statement of operations; cash from or used in operating, financing or investing activities on our consolidated cash flows statement upon adoption. In February 2016, the FASB issued ASU No. 2016-02, “Leases,” that requires lessees to recognize assets and liabilities on the balance sheet for most leases including operating leases. Lessees now classify leases as either finance or operating leases and lessors classify all leases as sales-type, direct financing or operating leases. The statement of operations presentation and expense recognition for lessees for finance leases is similar to that of capital leases under Accounting Standards Codification (“ASC”) 840 with separate interest and amortization expense with higher periodic expense in the earlier periods of a lease. For operating leases, the statement of operations presentation and expense recognition is similar to that of operating leases under ASC 840 with single lease cost recognized on a straight-line basis. This guidance is to be applied using a modified retrospective approach at the beginning of the earliest comparative period presented in the financial statements and is effective for annual periods beginning after December 15, 2018 and interim periods therein. Early adoption is permitted. We are currently analyzing the impact of ASU No. 2016-02 and, at this time, are unable to determine the impact of the new standard, on our consolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18, “Restricted Cash,” which requires entities to show the changes in total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash in the statement of cash flows. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions on the balance sheet. The reconciliation can be presented either on the face of the statement of cash flows or in the notes to the financial statements. The new standard is effective for public business entities for fiscal years beginning after December 15, 2017 and interim periods therein and is to be applied retrospectively. The guidance will be applied for the annual period beginning January 1, 2018 and presentation of reconciliations between cash and cash equivalents, and restricted cash balances will be applied retrospectively within the consolidated statement of cash flows. In January 2017, the FASB issued ASU No. 2017-04, “Intangibles–Goodwill and Other,” which eliminates the requirement to calculate the implied fair value of goodwill to measure a goodwill impairment charge. Under the new standard, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value. The new standard is effective for public business entities that are SEC filers for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The standard is to be applied on a prospective basis. We are currently analyzing the impact of ASU No. 2017-04 on our consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-07, “Compensation–Retirement Benefits,” which requires the presentation of the service cost component of the net periodic benefit cost in the same income statement line as other employee compensation costs arising from services rendered during the period. In addition, only the service cost component will be eligible for capitalization in assets. Disclosure of the line(s) used to present the other components of net periodic benefit cost, if the components are not presented separately in the income statement, is also required. The new standard is effective for public business entities for fiscal years beginning after December 15, 2017 and interim periods therein. The guidance on the presentation of the components of net periodic benefit cost in the income statement is to be applied retrospectively. The guidance limiting the capitalization of net periodic benefit cost in assets to the service cost component is to be applied prospectively. We are currently analyzing the impact of ASU No. 2017-07 on our consolidated financial statements. In October 2016, the FASB issued ASU No. 2016-16, “Intra-Entity Transfers of Assets Other Than Inventory,” which requires companies to account for the income tax effects of intercompany sales and transfers of assets other than inventory in the period in which the transfer occurs. The new standard is effective for public business entities for annual periods beginning after December 15, 2017 (i.e. 2018 for a calendar-year entity). The guidance will be applied for the annual period beginning January 1, 2018 using a modified retrospective approach with a cumulative catch-up adjustment to opening retained earnings. We elected to adopt ASU No. 2016-16 as of the first quarter of 2017, which required us to reflect any adjustments as of January 1, 2017. The primary impact of adoption was the recognition of a deferred tax asset of $34.9 million related to the excess of the tax basis over the consolidated book value basis in the intellectual property rights that were licensed from the U.S. parent company to our wholly-owned subsidiary in Switzerland during 2015 and a $2.1 million reversal of long-term prepaid taxes. Under previous guidance, companies were prohibited from recognizing an increase in tax basis and any income taxes incurred as a result of a sale or transfer of assets to companies that are part of a consolidated reporting entity. Given the full valuation allowance placed on the additional $34.9 million of deferred tax assets, the recognition upon adoption only required a $2.1 million adjustment to our retained earnings as of January 1, 2017 due to the adjustment of the prepaid tax asset. In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” The standard requires several changes including that equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) be measured at fair value with changes in fair value recognized in results of operations. These provisions will not impact the accounting for our investments in debt securities. The new guidance also changes certain disclosure requirements and other aspects of current U.S. GAAP. Amendments are to be applied as a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. The new standard will be effective for us on January 1, 2018. Based on our current investment holdings, the adoption of this standard will result in the reclassification of our investment in Calithera Biosciences, Inc. which is not expected to have a material impact on our financial position or results. In July 2015, the FASB issued ASU No. 2015-11, “Simplifying the Measurement of Inventory,” which requires inventory to be measured at the lower of cost and net realizable value rather than at the lower of cost or market value. The new standard is effective for public business entities for fiscal years beginning after December 15, 2016 and interim periods therein. The guidance is to be applied prospectively. We adopted ASU No. 2015-11 as of the first quarter of 2017 and the adoption had no impact on our consolidated financial statements. In December 2017, the FASB issued Staff Accounting Bulletin No. 118 (“SAB 118”) to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Cuts and Jobs Act of 2017 (the “Act”). In accordance with SAB 118, we have recorded provisional tax impacts related to the revaluation of deferred tax assets and liabilities as well as the temporary full expensing of certain business assets in our consolidated financial statements for the year ended December 31, 2017. The ultimate impact may differ from these provisional amounts, due to additional analysis, changes in interpretations and assumptions, and additional regulatory guidance that may be issued. The financial statement impact is expected to be complete when the 2017 U.S. corporate income tax return is filed in 2018. In January 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income ("GILTI") provisions of the Act. The GILTI provisions impose a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The guidance indicates that either accounting for deferred taxes related to GILTI inclusions or to treat any taxes on GILTI inclusions as period cost are both acceptable methods subject to an accounting policy election. Effective the first quarter of 2018, we have elected to treat any potential GILTI inclusions as a period charge in the future period in which it is incurred, and therefore this guidance had no impact on our consolidated financial statements for the year ended December 31, 2017.

Business Combination

12 Months Ended

Dec. 31, 2017

Business Combination

Business Combination

Note 2. Business Combination

Description of the Transaction

On June 1, 2016, pursuant to the Share Purchase Agreement, we completed the Acquisition, and acquired all of the outstanding shares of ARIAD Pharmaceuticals (Luxembourg) S.à.r.l., since renamed Incyte Biosciences Luxembourg S.à.r.l., the parent company of ARIAD’s European subsidiaries responsible for the development and commercialization of ICLUSIG (ponatinib) in the European Union (“EU”) and other countries including Switzerland, Norway, Turkey, Israel and Russia (the “Territory”) in exchange for an upfront payment of $147.5 million, including customary working capital adjustments (the “Upfront Payment”). ICLUSIG is approved in Europe for the treatment of patients with chronic myeloid leukemia and Philadelphia-positive acute lymphoblastic leukemia who are resistant to or intolerant of certain second generation BCR-ABL inhibitors and all patients who have the T3151 mutation. The acquisition of ARIAD Pharmaceuticals (Luxembourg) S.à.r.l. included a fully integrated and established pan-European team including medical, sales and marketing personnel. The existing platform and infrastructure acquired is expected to further our strategic plan and accelerate the establishment of our operations in Europe.

In connection with the closing of the Acquisition, we entered into an Amended and Restated Buy-in License Agreement with ARIAD (the “License Agreement”). Under the terms of the License Agreement, we were granted an exclusive license to develop and commercialize ICLUSIG in the Territory. ARIAD is eligible to receive from us tiered royalties ranging between 32% and 50% on net sales of ICLUSIG in the Territory. The royalties are subject to reduction for certain events related to exclusivity and, if necessary, any third-party patent rights. In addition, ARIAD is eligible to receive up to $135.0 million in potential future development and regulatory approval milestone payments for ICLUSIG in new oncology indications in the Territory (the “Milestones”), together with additional milestone payments for non-oncology indications, if approved, in the Territory. Under our agreement with ARIAD, we have agreed to fund a portion of the ongoing ICLUSIG clinical studies being conducted by ARIAD, OPTIC and OPTIC-2L, by paying up to $7.0 million in both 2016 and 2017 (the “Development Costs”). During the quarter ended September 30, 2017, ARIAD discontinued the OPTIC-2L clinical study.

The terms of the License Agreement also included a limited option for a potential future acquirer of ARIAD to purchase the European development and commercialization rights to ICLUSIG from us (the “Buy-Back Provision”). We concluded the Buy-Back Provision was not a derivative as it did not provide for explicit or implicit net settlement, cannot be readily settled net by a means outside of the contract, and does not provide for delivery of an asset that puts the recipient in a position that is not substantially different from net settlement. We also considered the probability of a potential future buyer exercising the Buy-Back Provision to be near zero and have concluded that any fair value assigned to this provision was de minimis. Takeda Pharmaceutical Company Limited acquired ARIAD in February 2017 but did not exercise the Buy-Back Provision, and the Buy-Back Provision lapsed.

Unless terminated earlier in accordance with its provisions, our obligations to pay full royalties under the License Agreement will continue to be in effect on a country-by-country basis until the latest to occur of (i) the expiration date of the composition patent in the relevant country, (ii) the expiration of any regulatory marketing exclusivity period or other statutory designation that provides similar exclusivity for the commercialization of ICLUSIG in such country and (iii) the seventh anniversary of the first commercial sale of ICLUSIG in such country. We will be obligated to pay royalties at a reduced rate for a specified period of time following such full royalty term. The License Agreement may be terminated in its entirety by us for convenience on 12 months’ notice after the third anniversary of the effective date of the License Agreement. The License Agreement may also be terminated by either party under certain other circumstances, including material breach, as set forth in the License Agreement.

Fair Value of Consideration Transferred

The fair value of consideration transferred totaled $440.5 million, which consisted of $147.5 million in cash pursuant to the Share Purchase Agreement, including net working capital adjustments, and $293.0 million of contingent consideration related to the License Agreement. Contingent consideration includes the future payments that we may pay to ARIAD for our royalty obligations on future net sales of ICLUSIG, as well as for any future potential milestone payments related to new oncology or non-oncology indications for ICLUSIG.

The fair value of contingent consideration was determined using an income approach based on estimated ICLUSIG revenues in the Territory for both the approved third line treatment, as well as the second line treatment that was under development and was therefore contingent on future clinical results and European Medicines Agency (“EMA”) approval. The probability of technical success (“PTS”) of the second line indication was estimated at 25% based on the early stage of development and competitive market landscape, and the estimated future cash flows for the second line indication were probability weighted accordingly. The total projected cash flows of the third line and second line indications were estimated over 18 years, and discounted to present value using a discount rate of 10%. In addition, based on the believed limited effectiveness of ICLUSIG beyond the existing oncology indications, the fact that no development is currently ongoing for any new oncology or any non-oncology indications, and the lack of intention by us, ARIAD, or another market participant, to develop ICLUSIG in additional oncology or non-oncology indications, the fair value of any cash flows for any new oncology or non-oncology indication was determined to be nil. The fair value of the contingent consideration was $293.0 million as of the Acquisition date.

Assets Acquired and Liabilities Assumed

The Acquisition has been accounted for as a business combination under the acquisition method of accounting. The following table summarizes the final fair values of the assets acquired and liabilities assumed as of the acquisition date (in thousands).


	Acquisition
	Fair Values
Current assets	$	21,363
Property and equipment		850
Restricted cash		432
Intangible assets(a)		283,000
Total identifiable assets		305,645
Current liabilities		(15,538)
Other long term liabilities		(5,226)
Total liabilities assumed		(20,764)
Goodwill(b)		155,593
Total fair value of consideration transferred	$	440,474

(a)As of the effective date of the Acquisition, identifiable intangible assets are required to be measured at fair value. The fair value measurement is based on significant inputs that are unobservable in the market and thus represents a Level 3 measurement. We used an income approach to estimate the fair value of the intangibles which includes licensed intellectual property and IPR&D. The assumptions used to estimate the cash flows of the licensed intellectual property included a discount rate of 15%, estimated gross margins of 98%, income tax rates ranging from 7.8% in periods in which we have established tax holidays to 13.8% thereafter, and operating expenses consisting of direct costs based on the anticipated level of revenues as well as the $7.0 million of research and development cost sharing payments we owe in 2016 and 2017. The assumptions used to estimate the cash flows of the IPR&D (which related to the potential approval of ICLUSIG as a second line treatment and, as described in Note 8 below, has subsequently been written off) included a PTS of 25%, discount rate of 16%, estimated gross margins of 98%, income tax rates ranging from 7.8% in periods in which we have established tax holidays to 13.8% thereafter, and operating expenses consisting of direct costs based on the anticipated level of revenues as well as probability weighted milestone payments estimated for 2020 related to the clinical results and potential approval of ICLUSIG as a second line treatment. The licensed intellectual property has a weighted-average useful life of approximately 12.5 years and will be amortized using the straight-line method. Amortization expense of the licensed intellectual property is recorded in cost of product revenues on the consolidated statement of operations. The IPR&D was considered an indefinite-lived intangible until the completion or abandonment of the related research and development activities.

(b)Goodwill is calculated as the difference between the acquisition date fair value of the consideration transferred and the fair values of the assets acquired and liabilities assumed. The Goodwill is related to the existing platform, infrastructure, and workforce which is expected to generate synergies and further our strategic plan in Europe. Goodwill is not amortized and none of the goodwill is expected to be deductible for tax purposes.

Acquisition-Related Costs

We incurred $1.6 million of transaction costs directly related to the Acquisition, which includes expenditures for advisory, legal, valuation, accounting and other similar services. These costs have been expensed in selling, general and administrative costs on the consolidated statements of operations during the year ended December 31, 2016.

Revenue and Net Loss of ARIAD Pharmaceuticals (Luxembourg) S.à.r.l.

The revenues of ARIAD Pharmaceuticals (Luxembourg) S.à.r.l. for the period from the acquisition date to December 31, 2016 were $29.6 million and net loss was $48.7 million. The net loss includes the effects of the Acquisition accounting adjustments and acquisition-related costs.

Pro Forma Impact of Business Combination

The following unaudited pro forma information presents condensed consolidated results of operations for the years ended December 31, 2016 and 2015, as if the Acquisition had occurred as of January 1, 2015 (in thousands).


	For the Years Ended
	December 31,
	2016		2015
Pro forma revenues	$	1,148,006	$	780,758
Pro forma net income (loss)	$	102,619	$	(69,892)

The unaudited pro forma condensed consolidated results of operations were prepared using the acquisition method of accounting and are based on the historical financial information of our company and the acquired business which has been adjusted for events that are (i) directly attributable to the Acquisition, (ii) factually supportable, and (iii) expected to have continuing impact on the combined results. The unaudited pro forma information reflects primarily the following adjustments:

To record amortization expense related to fair value adjustments recorded on the acquired definite lived intangibles;

To eliminate ARIAD Europe’s interest expense on the intercompany loan in accordance with the terms of the Acquisition;

To remove balances attributable to the ARIAD Australia entity which are not material. This entity was previously consolidated by ARIAD Europe; however it was not included in the Acquisition; and

To remove the recognition of revenue relating to distribution agreements in historic periods for those arrangements in which we have no continuing performance obligation and, therefore, the fair value of the assumed deferred revenue balance was zero.

The unaudited pro forma information is not necessarily indicative of the results that would have been obtained if the Acquisition had occurred as of the beginning of the period presented or that may occur in the future, and does not reflect future synergies, integration costs, or other such costs or savings.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1497-128463

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1490-128463

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e7008-128479

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1486-128463

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=73530397&loc=d3e4845-128472

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-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e7000-128479

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+ Details

Marketable Securities

12 Months Ended

Dec. 31, 2017

Marketable Securities

Marketable Securities

Note 3. Marketable Securities

The following is a summary of our marketable security portfolio as of December 31, 2017 and 2016, respectively.


			Net		Net
	Amortized		Unrealized		Unrealized		Estimated
	Cost		Gains		Losses		Fair Value
	(in thousands)
December 31, 2017
Debt securities (corporate and government)	$	271,401	$	—	$	(1,265)	$	270,136

December 31, 2016
Debt securities (corporate and government)	$	156,330	$	—	$	(127)	$	156,203

Our debt securities generally have contractual maturity dates of between 12 to 18 months.

Fair Value Measurements

FASB accounting guidance defines fair value as the price that would be received to sell an asset or paid to transfer a liability (“the exit price”) in an orderly transaction between market participants at the measurement date. The standard outlines a valuation framework and creates a fair value hierarchy in order to increase the consistency and comparability of fair value measurements and the related disclosures. In determining fair value we use quoted prices and observable inputs. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of us. The fair value hierarchy is broken down into three levels based on the source of inputs as follows:

Level 1—Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities.

Level 2—Valuations based on observable inputs and quoted prices in active markets for similar assets and liabilities.

Level 3—Valuations based on inputs that are unobservable and models that are significant to the overall fair value measurement.

Recurring Fair Value Measurements

Our marketable securities consist of investments in corporate debt securities and U.S. government securities that are classified as available-for-sale.

At December 31, 2017 and 2016, our Level 2 corporate debt securities were valued using readily available pricing sources which utilize market observable inputs, including the current interest rate and other characteristics for similar types of investments. Our long term investments classified as Level 1 were valued using the unadjusted closing stock price on The Nasdaq Stock Market.

Our policy is to recognize transfers into and transfers out of fair value hierarchy levels as of the end of the reporting period. During the year ended December 31, 2017, we transferred long term investments from Level 2 to Level 1 due to the lapse of marketability restrictions. The investments are now valued using the unadjusted closing stock price on The Nasdaq Stock Market. There were no transfers out of Level 1 to Level 2 during the period.

The following fair value hierarchy table presents information about each major category of our financial assets measured at fair value on a recurring basis as of December 31, 2017 (in thousands):


	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2017
Cash and cash equivalents	$	899,509	$	—	$	—	$	899,509
Debt securities (corporate and government)		—		270,136		—		270,136
Long term investments (Note 6)		134,356		—		—		134,356
Total assets	$	1,033,865	$	270,136	$	—	$	1,304,001

The following fair value hierarchy table presents information about each major category of our financial liabilities measured at fair value on a recurring basis as of December 31, 2017 (in thousands):


	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2017
Contingent consideration (Note 2)	$	—	$	—	$	287,000	$	287,000
Total liabilities	$	—	$	—	$	287,000	$	287,000

The following is a roll forward of our Level 3 liabilities (in thousands):


	Level 3
Balance at January 1, 2017	$	301,000
Contingent consideration earned during the period but not yet paid		(6,618)
Payments made during the period		(15,086)
Change in fair value of contingent consideration		7,704
Balance at December 31, 2017	$	287,000

The fair value of the contingent consideration was determined using an income approach based on estimated ICLUSIG revenues in the Territory for both the approved third line treatment, as well as the second line treatment that was under development until discontinued in the third quarter of 2017. The fair value of the contingent consideration is remeasured each reporting period, with changes in fair value recorded in the consolidated statements of operations. The change in fair value of the contingent consideration during the period ending December 31, 2017 is due primarily to the passage of time and a benefit of $24.0 million recorded during the third quarter related to the lack of expected future sales royalties payable due to the discontinued OPTIC-2L clinical trial.

We make payments to ARIAD quarterly based on the royalties or any additional milestone payments earned in the previous quarter. As of December 31, 2017, contingent consideration earned but not yet paid was $6.6 million and included in accrued and other current liabilities.

The following fair value hierarchy table presents information about each major category of our financial assets measured at fair value on a recurring basis as of December 31, 2016 (in thousands):


	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2016
Cash and cash equivalents	$	652,343	$	—	$	—	$	652,343
Debt securities (corporate and government)		—		156,203		—		156,203
Long term investment (Note 6)		31,987		—		—		31,987
Total assets	$	684,330	$	156,203	$	—	$	840,533


	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2016
Contingent consideration (Note 2)	$	—	$	—	$	301,000	$	301,000
Total liabilities	$	—	$	—	$	301,000	$	301,000

Net realized loss of $0.2 million from the sale of marketable securities was included in “Interest and other income, net” on the consolidated statements of operations for the year ended December 31, 2016.

Non-Recurring Fair Value Measurements

During the year ended December 31, 2017, there were no measurements required for any assets or liabilities at fair value on a non-recurring basis. During the year ended December 31, 2016, non-recurring fair value measurements related to the fair value of intangible assets and inventory acquired in the Acquisition which are discussed in further detail in Note 2.

Concentration of Credit Risk

12 Months Ended

Dec. 31, 2017

Concentration of Credit Risk

Concentrations of Credit Risk

Note 4. Concentrations of Credit Risk

In December 2009, we entered into a license, development and commercialization agreement with Lilly. In November 2009, we entered into a collaboration and license agreement with Novartis. The concentration of credit risk related to our collaborative partners is as follows:


	Percentage of Total Milestone and
	Contract Revenues for the
	Years Ended,
	December 31,
	2017		2016		2015
Collaboration Partner A	37	%	40	%	83	%
Collaboration Partner B	63	%	60	%	17	%

Collaboration Partner A and Collaboration Partner B comprised, in the aggregate, 47% and 23% of the accounts receivable balance as of December 31, 2017 and 2016, respectively.

In November 2011, we began commercialization and distribution of JAKAFI to a number of customers. Our product revenues are concentrated in a number of these customers. The concentration of credit risk related to our JAKAFI product revenues is as follows:


	Percentage of Total Net
	Product Revenues for the
	Years Ended,
	December 31,
	2017		2016		2015
Customer A	24	%	25	%	28	%
Customer B	15	%	17	%	19	%
Customer C	13	%	13	%	13	%
Customer D	8	%	9	%	9	%

We are exposed to risks associated with extending credit to customers related to the sale of products. Customer A, Customer B, Customer C and Customer D comprised, in the aggregate, 25% and 41% of the accounts receivable balance as of December 31, 2017 and 2016, respectively.

The concentration of credit risk relating to ICLUSIG product revenues or accounts receivable is not significant.

Inventory

12 Months Ended

Dec. 31, 2017

Inventory

Inventory

Note 5. Inventory

Our inventory balance consists of the following:


	December 31,
	2017		2016
	(in thousands)
Raw materials	$	1,062	$	109
Work-in-process		8,615		15,084
Finished goods		4,771		4,106
		14,448		19,299
Inventories-current		6,482		4,106
Inventories-non-current	$	7,966	$	15,193

Inventories, stated at the lower of cost and net realizable value, consist of raw materials, work-in-process and finished goods. The ICLUSIG inventories acquired on June 1, 2016 totaling $4.0 million were recorded at fair value less costs to sell, and therefore, resulted in a higher cost of ICLUSIG revenues over a one year period from the acquisition date. At December 31, 2017, $6.5 million of inventory was classified as current on the consolidated balance sheets as we expect this inventory to be consumed for commercial use within the next twelve months. At December 31, 2017, $8.0 million of inventory was classified as non‑current on the consolidated balance sheets as we did not expect this inventory to be consumed for commercial use within the next twelve months. We obtain some inventory components from a limited number of suppliers due to technology, availability, price, quality or other considerations. The loss of a supplier, the deterioration of our relationship with a supplier, or any unilateral violation of the contractual terms under which we are supplied components by a supplier could adversely affect our total revenues and gross margins.

JAKAFI raw materials and work-in-process inventory is not subject to expiration and the shelf life for finished goods inventory is 36 months from the start of manufacturing of the finished goods. ICLUSIG raw materials and work-in-process inventory is not subject to expiration and the shelf life for finished goods inventory is 24 months from the start of manufacturing of the finished goods. We evaluate for potential excess inventory by analyzing current and future product demand relative to the remaining product shelf life. We build demand forecasts by considering factors such as, but not limited to, overall market potential, market share, market acceptance and patient usage.

License Agreements	12 Months Ended
License Agreements	Dec. 31, 2017
License agreements
License Agreements	Note 6. License Agreements Novartis In November 2009, we entered into a Collaboration and License Agreement with Novartis. Under the terms of the agreement, Novartis received exclusive development and commercialization rights outside of the United States to our JAK inhibitor ruxolitinib and certain back‑up compounds for hematologic and oncology indications, including all hematological malignancies, solid tumors and myeloproliferative diseases. We retained exclusive development and commercialization rights to JAKAFI (ruxolitinib) in the United States and in certain other indications. Novartis also received worldwide exclusive development and commercialization rights to our MET inhibitor compound capmatinib and certain back‑up compounds in all indications. We retained options to co‑develop and to co‑promote capmatinib in the United States. Under this agreement, we received an upfront payment and immediate milestone payment totaling $210.0 million and were initially eligible to receive up to $1.2 billion in milestone payments across multiple indications upon the achievement of pre‑specified events, including up to $174.0 million for the achievement of development milestones, up to $495.0 million for the achievement of regulatory milestones and up to $500.0 million for the achievement of commercialization milestones. In April 2016, we amended this agreement to provide that Novartis has exclusive research, development and commercialization rights outside of the United States to ruxolitinib (excluding topical formulations) in the graft-versus-host-disease (“GVHD”) field. We became eligible to receive up to $75.0 million of additional potential development and regulatory milestones relating to GVHD. Exclusive of the upfront payment of $150.0 million received in 2009 and the immediate milestone of $60.0 million earned in 2010, we have recognized and received in the aggregate $132.0 million for the achievement of development milestones, $215.0 million for the achievement of regulatory milestones and $60.0 million for the achievement of sales milestones through December 31, 2017. During the year ended December 31, 2017, under this agreement, we recognized a $40.0 million sales milestone for Novartis achieving annual net sales of a JAK licensed product of $600.0 million and a $25.0 million development milestone based on the formal initiation by Novartis of a Phase III clinical trial evaluating ruxolitinib in GVHD. In 2016, we recognized a $5.0 million payment in exchange for the development and commercialization rights to ruxolitinib in GVHD outside of the United States and a $40.0 million regulatory milestone for the reimbursement of JAKAVI in Europe for the treatment of patients with polycythemia vera. In 2015, we recognized a $5.0 million development milestone based on the formal initiation by Novartis of a Phase II clinical trial evaluating capmatinib for a third indication, a $25.0 million regulatory milestone triggered by the Committee for Medicinal Products for Human Use of the European Medicines Agency adopting a positive opinion for JAKAVI (ruxolitinib) for the treatment of adult patients with polycythemia vera who are resistant to or intolerant of hydroxyurea, a $15.0 million regulatory milestone for the approval of JAKAVI in Japan for the treatment of patients with polycythemia vera, and a $20.0 million sales milestone for Novartis achieving annual net sales of a JAK licensed product of $300.0 million. In 2014, we recognized a $60.0 million regulatory milestone related to reimbursement of JAKAVI in Europe, a $25.0 million regulatory milestone for the approval of JAKAVI in Japan for the treatment of patients with myelofibrosis and a $7.0 million development milestone based on the formal initiation by Novartis of a Phase II clinical trial evaluating capmatinib in non-small cell lung cancer. In 2013, we recognized a $25.0 million development milestone based on the formal initiation by Novartis of a Phase II clinical trial evaluating capmatinib. In 2012, we recognized a $40.0 million regulatory milestone payment under this agreement for the achievement of a predefined milestone for the European Union regulatory approval of JAKAVI. In 2011, we recognized a $15.0 million development milestone for the achievement of a predefined milestone in the Phase I dose‑escalation trial for capmatinib in patients with solid tumors and a $10.0 million regulatory milestone for the approval of JAKAFI in the United States. In 2010, we recognized $50.0 million in development milestones for the initiation of the global Phase III trial, RESPONSE, in patients with polycythemia vera. We determined that each of these milestones were substantive as their achievement required substantive efforts by us and was at risk until the milestones were ultimately achieved. We also are eligible to receive tiered, double‑digit royalties ranging from the upper‑teens to the mid‑twenties on future JAKAVI net sales outside of the United States, and tiered, worldwide royalties on future capmatinib net sales that range from 12% to 14%. Since the achievement of the $60.0 million regulatory milestone related to reimbursement of JAKAVI in Europe in September 2014, we are obligated to pay to Novartis tiered royalties in the low single-digits on future JAKAFI net sales within the United States. During the years ended December 31, 2017, 2016 and 2015, such royalties payable to Novartis on net sales within the United States totaled $50.5 million, $36.8 million and $24.4 million, respectively, and are reflected in cost of product revenues on the consolidated statements of operations. Each company is responsible for costs relating to the development and commercialization of ruxolitinib in its respective territories, with costs of collaborative studies shared equally. Novartis is also responsible for all costs relating to the development and commercialization of capmatinib. The Novartis agreement will continue on a program‑by‑program basis until Novartis has no royalty payment obligations with respect to such program or, if earlier, the termination of the agreement or any program in accordance with the terms of the agreement. Royalties are payable by Novartis on a product‑by‑product and country‑by‑country basis until the latest to occur of (i) the expiration of the last valid claim of the licensed patent rights covering the licensed product in the relevant country, (ii) the expiration of regulatory exclusivity for the licensed product in such country and (iii) a specified period from first commercial sale in such country of the licensed product by Novartis or its affiliates or sublicensees. The agreement may be terminated in its entirety or on a program‑by‑program basis by Novartis for convenience. The agreement may also be terminated by either party under certain other circumstances, including material breach. We determined that there were two deliverables under the agreement: (i) the ex-U.S. license for ruxolitinib and (ii) our obligations in connection with our participation on the joint development committee for myelofibrosis and polycythemia vera/essential thrombocythemia. We concluded that these deliverables should be accounted for as a single unit of accounting and the $150.0 million upfront payment received in December 2009 and the immediate $60.0 million milestone payment received in January 2010 should be recognized on a straight-line basis through December 2013, when we estimated we would complete our obligations in connection with our participation on the joint development committee for myelofibrosis and polycythemia vera, our estimated performance period under the agreement. We completed this substantive performance obligation related to this arrangement in December 2013. At December 31, 2009, we recorded $10.9 million of reimbursable costs incurred prior to the effective date of the agreement as deferred revenue on the consolidated balance sheet. These costs were recognized on a straight-line basis through December 2013 consistent with the aforementioned upfront and milestone payments. Future reimbursable costs incurred after the effective date of the agreement with Novartis are recorded net against the related research and development expenses. At December 31, 2017 and 2016, $1.6 million and $0.6 million, respectively, of reimbursable costs were included in accounts receivable on the consolidated balance sheets. Research and development expenses for the years ended December 31, 2017, 2016 and 2015 were net of $3.0 million, $0.7 million, and $1.6 million, respectively, of costs reimbursed by Novartis. Milestone and contract revenue under the Novartis agreement was $65.0 million, $45.0 million and $65.0 million for the years ended December 31, 2017, 2016 and 2015, respectively. In addition, for the years ended December 31, 2017, 2016 and 2015, we recorded $151.7 million, $110.7 million and $74.8 million, respectively, of product royalty revenues related to Novartis net sales of JAKAVI outside the United States. At December 31, 2017 and 2016, $47.7 million and $33.3 million, respectively, of product royalties were included in accounts receivable on the consolidated balance sheets. Lilly - Baricitinib In December 2009, we entered into a License, Development and Commercialization Agreement with Lilly. Under the terms of the agreement, Lilly received exclusive worldwide development and commercialization rights to our JAK inhibitor baricitinib, and certain back‑up compounds for inflammatory and autoimmune diseases. We received an upfront payment of $90.0 million, and were initially eligible to receive up to $665.0 million in substantive milestone payments across multiple indications upon the achievement of pre‑specified events, including up to $150.0 million for the achievement of development milestones, up to $365.0 million for the achievement of regulatory milestones and up to $150.0 million for the achievement of commercialization milestones. Exclusive of the upfront payment of $90.0 million received in 2009, we have recognized and received, in aggregate, $129.0 million for the achievement of development milestones and $135.0 million for the achievement of regulatory milestones through December 31, 2017. In April 2017, we and Lilly announced that the FDA had issued a complete response letter for the New Drug Application of baricitinib as a once-daily oral medication for the treatment of moderate-to-severe rheumatoid arthritis. The letter indicated that the FDA was unable to approve the application in its current form. Specifically, the FDA indicated that additional clinical data are needed to determine the most appropriate doses. The FDA also stated that additional data are necessary to further characterize safety concerns across treatment arms. In December 2017, Lilly announced that the NDA for baricitinib had been resubmitted and included new safety and efficacy data. The FDA classified the application as a Class II resubmission, which started a new six-month review cycle. During the year ended December 31, 2017, under this agreement, we recognized a $30.0 million development milestone for the first patient treated in the atopic dermatitis Phase III program for baricitinib, a $15.0 million regulatory milestone for the approval of baricitinib for the treatment of rheumatoid arthritis by Japan’s Ministry of Health, Labor and Welfare and a $65.0 million regulatory milestone for the approval of baricitinib for the treatment of moderate-to-severe rheumatoid arthritis in adult patients by the European Commission. In 2016, we recognized a $35.0 million regulatory milestone for the submission of an NDA to the FDA for the approval of oral once-daily baricitinib for the treatment of moderate-to-severe rheumatoid arthritis and a $20.0 million regulatory milestone for the submission of a Marketing Authorization Application to the European Medicines Agency for the approval of oral once-daily baricitinib for the treatment of moderate-to-severe rheumatoid arthritis. In 2012, we recognized a $50.0 million development milestone for the initiation of the rheumatoid arthritis Phase III program for baricitinib. In 2010, we recognized a $30.0 million development milestone based upon the initial three month data in the Phase IIa clinical trial of baricitinib for the treatment of rheumatoid arthritis and a $19.0 million development milestone for the Phase IIb clinical trial initiation of baricitinib for the treatment of rheumatoid arthritis. We determined that each of these milestones were substantive as their achievement required substantive efforts by us and was at risk until the milestones were ultimately achieved. In July 2010, we elected to co-develop baricitinib with Lilly in rheumatoid arthritis and we are responsible for funding 30% of the associated future global development costs for this indication from the initiation of the Phase IIb trial through regulatory approval, including post-launch studies required by a regulatory authority. In January 2017, we exercised our co-development options in psoriatic arthritis and atopic dermatitis to fund 30% of future global development costs through regulatory approval, including post-launch studies required by a regulatory authority. We have also exercised our co-development options in systemic lupus erythematosus and axial spondyloarthritis, should Lilly decide to progress into a pivotal program in these indications. We retained options to co-develop our JAK1/JAK2 inhibitors with Lilly on a compound-by-compound and indication-by-indication basis. Lilly is responsible for all costs relating to the development and commercialization of the compounds unless we elect to co-develop any compounds or indications. If we elect to co-develop any compounds and/or indications, we would be responsible for funding 30% of the associated future global development costs from the initiation of a Phase IIb trial through regulatory approval, including post-launch studies required by a regulatory authority. We would receive an incremental royalty rate increase across all tiers resulting in effective royalty rates ranging up to the high twenties on potential future global net sales for compounds and/or indications that we elect to co-develop. For indications that we elect not to co‑develop, we would receive tiered, double‑digit royalty payments on future global net sales with rates ranging up to 20% if the product is successfully commercialized. We previously had retained an option to co-promote products in the United States but, in March 2016, we waived our co-promotion option as part of an amendment to the agreement. In February 2017, the European Commission approved baricitinib, which is marketed as OLUMIANT, for the treatment of moderate-to-severe rheumatoid arthritis in adult patients. Research and development expenses recorded under the Lilly agreement representing 30% of the global development costs for baricitinib for the treatment of rheumatoid arthritis were $40.8 million, $27.3 million and $36.0 million, respectively, for the years ended December 31, 2017, 2016 and 2015. We have retained certain mechanisms to give us cost protection as baricitinib advances in clinical development. We can defer our portion of co‑development study costs by indication if they exceed a predetermined level. This deferment would be credited against future milestones or royalties and we would still be eligible for the full incremental royalties related to the co‑development option. In addition, even if we have started co‑development funding for any indication, we can at any time opt out and stop future co‑development cost sharing. If we elect to do this we would still be eligible for our base royalties plus an incremental, pro‑rated royalty commensurate with our contribution to the total co‑development cost for those indications for which we co‑funded. The Lilly agreement will continue until Lilly no longer has any royalty payment obligations or, if earlier, the termination of the agreement in accordance with its terms. Royalties are payable by Lilly on a product‑by‑product and country‑by‑country basis until the latest to occur of (i) the expiration of the last valid claim of the licensed patent rights covering the licensed product in the relevant country, (ii) the expiration of regulatory exclusivity for the licensed product in such country and (iii) a specified period from first commercial sale in such country of the licensed product by Lilly or its affiliates or sublicensees. The agreement may be terminated by Lilly for convenience, and may also be terminated under certain other circumstances, including material breach. We determined that there were two deliverables under the agreement: (i) the worldwide license and (ii) our obligations in connection with a co‑development option. We concluded that these deliverables should be accounted for as a single unit of accounting and the $90.0 million upfront payment should be recognized on a straight-line basis as revenue through December 2016, our estimated performance period under the agreement. We completed our substantive performance obligation related to this arrangement in December 2016. Milestone and contract revenue under the Lilly agreement was $110.0 million, $67.5 million and $12.9 million, respectively, for the years ended December 31, 2017, 2016 and 2015. In addition, for the year ended December 31, 2017, we recorded $9.1 million of product royalty revenues related to Lilly net sales of OLUMIANT outside the United States. At December 31, 2017, $4.6 million of product royalties were included in accounts receivable on the consolidated balance sheets. Lilly – Ruxolitinib In March 2016, we entered into an amendment to the agreement with Lilly that amended the non-compete provision of the agreement to allow us to engage in the development and commercialization of ruxolitinib in the GVHD field. We paid Lilly an upfront payment of $35.0 million and Lilly is eligible to receive up to $40.0 million in additional regulatory milestone payments relating to ruxolitinib in the GVHD field. During the year ended December 31, 2016, the $35.0 million upfront payment was recorded in research and development expense in our consolidated statements of operations. Pfizer In January 2006, we entered into a Collaborative Research and License Agreement with Pfizer for the pursuit of our CCR2 antagonist program. Pfizer gained worldwide development and commercialization rights to our portfolio of CCR2 antagonist compounds. Pfizer’s rights extend to the full scope of potential indications, with the exception of multiple sclerosis and autoimmune nephritides, where we retained worldwide rights, along with certain compounds. In the absence of activity on the portfolio, we and Pfizer are currently reviewing strategic options for disposition. Agenus In January 2015, we entered into a License, Development and Commercialization Agreement with Agenus Inc. and its wholly-owned subsidiary, 4-Antibody AG (now known as Agenus Switzerland Inc.), which we collectively refer to as Agenus. Under this agreement, the parties have agreed to collaborate on the discovery of novel immuno-therapeutics using Agenus’ antibody discovery platforms. The agreement became effective on February 18, 2015, upon the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976. Upon closing of the agreement, we paid Agenus total consideration of $60.0 million. Of the $60.0 million, $39.8 million was allocated to our stock purchase in Agenus Inc. and was recorded as a long term investment on the consolidated balance sheets and $20.2 million was allocated to research and development expense on the consolidated statement of operations during the year ended December 31, 2015. In February 2017, we and Agenus amended this agreement (the “Amended Agreement”). Under the terms of the Amended Agreement, we received exclusive worldwide development and commercialization rights to four checkpoint modulators directed against GITR, OX40, LAG-3 and TIM-3. In addition to the initial four program targets, we and Agenus have the option to jointly nominate and pursue additional targets within the framework of the collaboration, and in November 2015, three more targets were added. Targets may be designated profit-share programs, where all costs and profits are shared equally by us and Agenus, or royalty-bearing programs, where we are responsible for all costs associated with discovery, preclinical, clinical development and commercialization activities. The programs relating to GITR and OX40 and two of the undisclosed targets were profit-share programs until February 2017, while the other targets currently under collaboration are royalty-bearing programs. The Amended Agreement converted the programs relating to GITR and OX40 to royalty-bearing programs and removed from the collaboration the profit-share programs relating to the two undisclosed targets, with one reverting to us and one reverting to Agenus. Should any of those removed programs be successfully developed by a party, the other party will be eligible to receive the same milestone payments as the royalty-bearing programs and royalties at a 15% rate on global net sales. There are currently no profit-share programs. For each royalty-bearing product other than GITR and OX40, Agenus will be eligible to receive tiered royalties on global net sales ranging from 6% to 12%. For GITR and OX40, Agenus will be eligible to receive 15% royalties on global net sales. Under the Amended Agreement, we paid Agenus $20.0 million in accelerated milestones relating to the clinical development of the GITR and OX40 programs, which is recorded in research and development expense on the consolidated statement of operations during the year ended December 31, 2017. Agenus is eligible to receive up to an additional $510.0 million in future contingent development, regulatory and commercialization milestones across all programs in the collaboration. The agreement may be terminated by us for convenience upon 12 months’ notice and may also be terminated under certain other circumstances, including material breach. In connection with the Amended Agreement, we also agreed to purchase 10.0 million shares of Agenus Inc. common stock for an aggregate purchase price of $60.0 million in cash, or $6.00 per share. We completed the purchase of the shares on February 14, 2017, when the closing price on The Nasdaq Stock Market for Agenus Inc. shares was $4.40 per share. The shares we acquired were not registered under the Securities Act of 1933 on the purchase date and were subject to certain security specific restrictions for a period of time, and accordingly, we estimated a discount for lack of marketability on the shares on the issuance date of $4.5 million, which resulted in a net fair value of the shares on the issuance date of $39.5 million. Therefore, of the total consideration paid of $60.0 million, $39.5 million was allocated to our stock purchase in Agenus Inc. and was recorded within long term investments on the consolidated balance sheets and $20.5 million was allocated to research and development expense on the consolidated statement of operations during the year ended December 31, 2017. We have concluded Agenus Inc. is not a VIE because it has sufficient equity to finance its activities without additional subordinated financial support and its at-risk equity holders have the characteristics of a controlling financial interest. From the date of our initial stock purchase in February 2015 and up to the date of our second stock purchase in February 2017, we owned between 9% and 11% of the outstanding shares of Agenus Inc. common stock. As a result of our February 2017 stock purchase, we owned approximately 18% of the outstanding shares of Agenus Inc. common stock as of December 31, 2017. We concluded that we have the ability to exercise significant influence, but not control, over Agenus Inc. based primarily on our ownership interest, the fact that we have been the largest Agenus stockholder since the date of our initial stock purchase, the level of intra-entity transactions between us and Agenus related to development expenses, as well as other qualitative factors. We have elected the fair value option to account for our long term investment in Agenus Inc. whereby the investment is marked to market through earnings in each reporting period. We believe the fair value option to be the most appropriate accounting method to account for securities in publicly held collaborators for which we have significant influence. For the years ended December 31, 2017, 2016 and 2015, we recorded an unrealized loss of $13.6 million, $3.3 million and $4.6 million, respectively, based on the change in the market price of Agenus Inc.’s common stock from the date of purchase. The fair market value of our long term investment in Agenus Inc. as of December 31, 2017 and 2016 was $57.9 million and $32.0 million, respectively. Research and development expenses for the years ended December 31, 2017, 2016 and 2015, also included $19.5 million, $17.5 million and $14.4 million, respectively, of development costs incurred pursuant to the Agenus arrangement. At December 31, 2017 and 2016, a total of $3.2 million and $11.4 million, respectively, of such costs were included in accrued and other liabilities on the consolidated balance sheet. Hengrui In September 2015, we entered into a License and Collaboration Agreement with Jiangsu Hengrui Medicine Co., Ltd. (“Hengrui”). Under the terms of this agreement, we received exclusive development and commercialization rights worldwide, with the exception of Mainland China, Hong Kong, Macau and Taiwan, to INCSHR1210, an investigational PD-1 monoclonal antibody, and certain back-up compounds. Under the terms of this agreement, we paid Hengrui an upfront payment of $25.0 million in 2015 which was recorded in research and development expense on the consolidated statement of operations. Hengrui was also eligible to receive potential milestone payments of up to $770.0 million, consisting of $90.0 million for regulatory approval milestones, $530.0 million for commercial performance milestones, and $150.0 million for a clinical superiority milestone. Also, Hengrui was eligible to receive tiered royalties in the high single-digits to mid-double digits based on net sales in our territories. Each company was responsible for costs relating to the development and commercialization of the PD-1 monoclonal antibody in its respective territories. In February 2018, Incyte and Hengrui agreed to terminate the collaboration, pursuant to the terms of the License and Collaboration Agreement. Research and development expenses for the years ended December 31, 2017, 2016 and 2015, included $3.2 million, $9.8 million and $0.5 million, respectively, of development costs incurred pursuant to the Hengrui agreement. Merus In December 2016, we entered into a Collaboration and License Agreement with Merus N.V. Under this agreement, which became effective in January 2017, the parties have agreed to collaborate with respect to the research, discovery and development of bispecific antibodies utilizing Merus’ technology platform. The collaboration encompasses up to eleven independent programs, including two of Merus’ current preclinical immuno-oncology discovery programs. We received exclusive development and commercialization rights outside of the United States to products and product candidates resulting from one of Merus’ current preclinical discovery programs, referred to as “Program 1.” We also received worldwide exclusive development and commercialization rights to products and product candidates resulting from the other current Merus preclinical discovery program that is subject to the collaboration and to up to nine additional programs. Merus retained exclusive development and commercialization rights in the United States to products and product candidates resulting from Program 1 and options, subject to certain conditions, to co-fund development of products resulting from two other programs in exchange for a share of profits in the United States. Should Program 1 fail to successfully complete IND-enabling toxicology studies, Merus would be granted an additional option to co-fund development of a program in exchange for a share of profits in the United States. All costs related to the collaboration are subject to joint research and development plans. Each party will share equally the costs of mutually agreed global development activities for Program 1, and fund itself any independent development activities in its territory. We will be responsible for all research, development and commercialization costs relating to all other programs, subject to Merus’ election to co-fund development and co-detail described above. If Merus exercises its co-funding option for a program, Merus would be responsible for funding 35% of the associated future global development costs and, for certain of such programs, would be responsible for reimbursing us for certain development costs incurred prior to the option exercise. In February 2017, we paid Merus an upfront non-refundable payment of $120.0 million, which is recorded in research and development expense on the consolidated statement of operations. For each program as to which Merus does not have commercialization or co-development rights, Merus will be eligible to receive up to $100.0 million in future contingent development and regulatory milestones and up to $250.0 million in commercialization milestones as well as tiered royalties ranging from 6% to 10% of global net sales. For each program as to which Merus exercises its option to co-fund development, Merus will be eligible to receive a 50% share of profits (or sustain 50% of any losses) in the United States and be eligible to receive tiered royalties ranging from 6% to 10% of net sales of products outside of the United States. If Merus opts to cease co-funding a program as to which it exercised its co-development option, then Merus will no longer receive a share of profits in the United States but will be eligible to receive the same milestones from the co-funding termination date and the same tiered royalties described above with respect to non-co-developed programs and, depending on the stage at which Merus chose to cease co-funding development costs, additional royalties ranging up to 4% of net sales in the United States. For Program 1, we and Merus will each be eligible to receive tiered royalties on net sales in the other party’s territory at rates ranging from 6% to 10%. The Merus agreement will continue on a program-by-program basis until we have no royalty payment obligations with respect to such program or, if earlier, the termination of the agreement or any program in accordance with the terms of the agreement. The agreement may be terminated in its entirety or on a program-by-program basis by us for convenience. The agreement may also be terminated by either party under certain other circumstances, including material breach, as set forth in the agreement. If the agreement is terminated with respect to one or more programs, all rights in the terminated programs revert to Merus, subject to payment to us of a reverse royalty of up to 4% on sales of future products, if Merus elects to pursue development and commercialization of products arising from the terminated programs. In addition, in December 2016, we entered into a Share Subscription Agreement with Merus, pursuant to which we agreed to purchase 3.2 million common shares of Merus for an aggregate purchase price of $80.0 million in cash, or $25.00 per share. We agreed to certain standstill provisions whereby we are obligated to refrain from taking certain actions with respect to Merus or Merus’ common shares during a period ending on the earliest of (a) three years from the closing date of our share purchase, (b) the date Merus publicly announces any merger or similar business combination or another party announces an intention to acquire a substantial portion of Merus’ securities, and (c) the termination of the Collaboration and License Agreement. The standstill provisions are subject to certain exceptions, including an exception that allows us to maintain our percentage ownership following equity financings by Merus. We also agreed, subject to limited exceptions, not to sell or otherwise transfer any of our Merus shares for a period, referred to as the Lock-Up Period, ending on the earlier of 18 months after the closing date of the sale of the Shares or the end of the standstill period. In addition, if the standstill period has not been terminated earlier upon the occurrence of certain events, for a period of three years after the Lock-Up Period, we will be restricted from selling or otherwise transferring more than one-third of our Merus shares during any 12-month period or 10% of our Merus shares during any three-month period, unless Merus consents otherwise. We have further agreed that during the standstill period, we will vote all of our Merus shares in accordance with the recommendation of a majority of Merus’ supervisory board. However, we may vote our Merus shares at our own discretion for certain extraordinary matters, including a change in control of Merus. Merus has agreed to customary resale registration rights with respect to our Merus shares; however, any such resales will be subject to the Lock-Up Period and volume limitations on sale and transfer described above. We completed the purchase of the shares on January 23, 2017 when the closing price on The Nasdaq Stock Market for Merus shares was $24.50 per share. The shares we acquired were not registered under the Securities Act of 1933 on the purchase date and were subject to certain security specific restrictions for a period of time, and accordingly, we estimated a discount for lack of marketability on the shares on the issuance date of $5.6 million, which resulted in a net fair value of the shares on the issuance date of $72.8 million. Of the total consideration paid of $80.0 million, $72.8 million was allocated to our stock purchase in Merus and was recorded as a long term investment on the consolidated balance sheets and $7.2 million was allocated to research and development expense on the consolidated statement of operations during the year ended December 31, 2017. The fair market value of our total long term investment in Merus as of December 31, 2017 was $62.1 million. We have concluded Merus is not a VIE because it has sufficient equity to finance its activities without additional subordinated financial support and its at-risk equity holders have the characteristics of a controlling financial interest. As of December 31, 2017, we owned approximately 17% of the outstanding shares of Merus common stock and conclude that we have the ability to exercise significant influence, but not control, over Merus based primarily on our ownership interest, the level of intra-entity transactions between us and Merus related to development expenses, as well as other qualitative factors. We have elected the fair value option to account for our long term investment in Merus whereby the investment is marked to market through earnings in each reporting period. We believe the fair value option to be the most appropriate accounting method to account for securities in publicly held collaborators for which we have significant influence. For the year ended December 31, 2017, we recorded an unrealized loss of $10.7 million, based on the change in fair value of Merus’ common stock from the date of purchase. Research and development expenses for the year ended December 31, 2017 included $6.5 million of additional development costs incurred pursuant to the Merus agreement. At December 31, 2017, a total of $2.1 million of such costs were included in accrued and other liabilities on the consolidated balance sheet. Calithera In January 2017, we entered into a Collaboration and License Agreement with Calithera Biosciences, Inc. Under this agreement, we received an exclusive, worldwide license to develop and commercialize small molecule arginase inhibitors, including CB-1158, which is currently in Phase I clinical trials, for hematology and oncology indications. We have agreed to co-fund 70% of the global development costs for the development of the licensed products for hematology and oncology indications. Calithera will have the right to conduct certain clinical development under the collaboration, including combination studies of a licensed product with a proprietary compound of Calithera. We will be entitled to 60% of the profits and losses from net sales of licensed product in the United States, and Calithera will have the right to co-detail licensed products in the United States, and we have agreed to pay Calithera tiered royalties ranging from the low to mid-double digits on net sales of licensed products outside the United States. Calithera may opt out of its co-funding obligation, in which case the U.S. profit sharing will no longer be in effect, and we have agreed to pay Calithera tiered royalties ranging from the low to mid-double digits on net sales of licensed products both in the United States and outside the United States, and additional royalties to reimburse Calithera for previously incurred development costs. In January 2017, we paid Calithera an upfront license fee of $45.0 million and have agreed to pay potential development, regulatory and sales milestone payments of over $430.0 million if the profit share is in effect, or $750.0 million if the profit share terminates. The Calithera agreement will continue on a product-by-product and country-by-country basis for so long as we are developing or commercializing products in the United States (if the parties are sharing profits in the United States) and until we have no further royalty payment obligations, unless earlier terminated according to the terms of the agreement. The agreement may be terminated in its entirety or on a product-by-product and/or a country-by-country basis by us for convenience. The agreement may also be terminated by us for Calithera’s uncured material breach, by Calithera for our uncured material breach and by either party for bankruptcy or patent challenge. If the agreement is terminated early with respect to one or more products or countries, all rights in the terminated products and countries revert to Calithera. In addition, in January 2017, we entered into a Stock Purchase Agreement with Calithera for the purchase of 1,720,430 common shares of Calithera for an aggregate purchase price of $8.0 million in cash, or $4.65 per share. We completed the purchase of the shares on January 30, 2017 when the closing price on The Nasdaq Stock Market was $6.75 per share. The shares we acquired were registered under the Securities Act of 1933 on the purchase date and there were no security specific restrictions for these shares, and therefore the value of the 1.7 million shares acquired by us was $11.6 million. We paid total consideration of $53.0 million to Calithera, composed of the $45.0 million upfront license fee and the $8.0 million stock purchase price. Of the $53.0 million, $11.6 million was allocated to our stock purchase in Calithera and was recorded within long term investments on the consolidated balance sheets and $41.4 million was allocated to research and development expense on the consolidated statement of operations during the year ended December 31, 2017. The fair market value of our long term investment in Calithera as of December 31, 2017 was $14.4 million. We have concluded Calithera is not a VIE because it has sufficient equity to finance its activities without additional subordinated financial support and its at-risk equity holders have the characteristics of a controlling financial interest. As of December 31, 2017, we owned approximately 5% of the outstanding shares of Calithera common stock and there are several other stockholders who hold larger positions of Calithera. As we do not hold a significant position of the voting shares of Calithera and lack the qualitative characteristics associated with the ability to exercise significant influence, our ownership interest does not meet the criteria to be accounted for as an equity method investment. We intend to hold the investment in Calithera for the foreseeable future and therefore, we are accounting for our shares held in Calithera as an available-for-sale investment, whereby the investment is marked to market each period with unrealized gains and losses recorded in accumulated other comprehensive income (loss). Given our intent to hold the investment for the foreseeable future, we have classified the investment within long term investments on the accompanying balance sheet. For the year ended December 31, 2017, we recorded an unrealized gain of $2.8 million within other comprehensive income (loss) based on the change in fair value of Calithera’s common stock from the date of purchase. In March 2017, Calithera earned a $12.0 million milestone payment from us for the achievement of pharmacokinetic and pharmacodynamics goals for CB-1158 which is recorded in research and development expense on our consolidated statement of operations during the year ended December 31, 2017. Research and development expenses for the year ended December 31, 2017 also included $23.4 million of additional development costs incurred pursuant to the Calithera agreement. At December 31, 2017, a total of $0.9 million of such costs were included in accrued and other liabilities on the consolidated balance sheet. MacroGenics In October 2017, we entered into a Global Collaboration and License Agreement with MacroGenics, Inc. Under this agreement, we received exclusive development and commercialization rights worldwide to MacroGenics’ MGA012, an investigational monoclonal antibody that inhibits PD-1. Except as set forth in the succeeding sentence, we will have sole authority over and bear all costs and expenses in connection with the development and commercialization of MGA012 in all indications, whether as a monotherapy or as part of a combination regimen. MacroGenics has retained the right to develop and commercialize, at its cost and expense, its pipeline assets in combination with MGA012. In addition, MacroGenics has the right to manufacture a portion of both companies’ global clinical and commercial supply needs of MGA012. In December 2017, we paid MacroGenics an upfront payment of $150.0 million which is recorded in research and development expense on our consolidated statement of operations. MacroGenics will be eligible to receive up to $420.0 million in future contingent development and regulatory milestones, and up to $330.0 million in commercial milestones as well as tiered royalties ranging from 15% to 24% of global net sales. The MacroGenics agreement will continue until we are no longer commercializing, developing or manufacturing MGA012 or, if earlier, the termination of the agreement in accordance with its terms. The agreement may be terminated in its entirety or on a licensed product by licensed product basis by us for convenience. The agreement may also be terminated by either party under certain other circumstances, including material breach, as set forth in the agreement.

Property and Equipment

12 Months Ended

Dec. 31, 2017

Property and Equipment

Property and Equipment

Note 7. Property and Equipment

Property and equipment consists of the following:


	December 31,
	2017		2016
	(in thousands)
Office equipment	$	14,674	$	9,243
Laboratory equipment		48,807		37,203
Computer equipment		51,351		38,184
Land		5,350		4,125
Building and leasehold improvements		214,245		130,734
		334,427		219,489
Less accumulated depreciation and amortization		(74,664)		(51,810)
Property and equipment, net	$	259,763	$	167,679

Depreciation expense, including amortization expense of leasehold improvements, was $24.6 million, $14.2 million and $11.3 million for the years ended December 31, 2017, 2016 and 2015, respectively.

In April 2016, we completed our purchase of the previously leased land and building comprising approximately 190,000 square feet of laboratory and office space located in Wilmington, Delaware. We previously accounted for the lease as a direct financing arrangement. In total, upon completion of the purchase, we paid $81.3 million, including closing costs, for the purchase of the land and building and our direct financing obligation related to the lease was relieved. We recorded the difference between the amount paid for the purchase of the land and building ($81.3 million) and the remaining direct financing obligation on the purchase date ($45.9 million) as property and equipment. A total of $3.8 million was allocated to land and the remaining $31.6 million was allocated to buildings and leasehold improvements, which we estimated using the assistance of a third-party valuation specialist. The land is not being amortized and we are depreciating the building over its estimated useful life of 40 years. In addition, the restricted investments related to the direct financing lease were released upon closing of the agreement of sale.

In September 2016, we entered into two agreements to purchase two buildings at 1701 Augustine Cut-off in Wilmington, Delaware. The purchase closed in March 2017 for a total purchase price of approximately $8.1 million, consisting of $1.2 million of land and $6.9 million of buildings and leasehold improvements, which we estimated using the assistance of a third-party valuation specialist.

In October 2017, we completed the construction of a 154,000 square foot office building located in Wilmington, Delaware totaling approximately $91.3 million and are depreciating the building over its estimated useful life of 40 years.

Intangible Assets and Goodwill

12 Months Ended

Dec. 31, 2017

Intangible Assets and Goodwill

Intangible Assets and Goodwill

Note 8. Intangible Assets and Goodwill

Intangible Assets, Net

The components of intangible assets were as follows (in thousands, except for useful life):


				Balance at December 31, 2017					Balance at December 31, 2016
	Weighted-	Gross					Net		Gross				Net
	Average Useful	Carrying			Accumulated		Carrying		Carrying		Accumulated		Carrying
	Lives (Years)	Amount			Amortization		Amount		Amount		Amortization		Amount
Finite-lived intangible assets:
Licensed IP(1)	12.5	$	271,000		$	34,099	$	236,901	$	271,000	$	12,563	$	258,437
Indefinite-lived intangible assets:
Acquired IPR&D(1)	N/A		—			—		—		12,000		—		12,000
		$	271,000		$	34,099	$	236,901	$	283,000	$	12,563	$	270,437

(1) We acquired certain intangible assets as part of the Acquisition, as described further in Note 2. During the third quarter of 2017, we wrote-off the acquired IPR&D asset of $12.0 million due to the discontinuation of the OPTIC-2L study. The write-off of the IPR&D asset was recorded in research and development expense on the consolidated statements of operations.

Amortization expense was $21.5 million and $12.6 million for the years ended December 31, 2017 and 2016, respectively, and is recorded in cost of product revenues on the consolidated statement of operations. Estimated aggregate amortization expense based on the current carrying value of amortizable intangible assets will be as follows for the years ending December 31 (in thousands):


		2018		2019		2020		2021		2022		Thereafter
Amortization expense	$	21,536	$	21,536	$	21,536	$	21,536	$	21,536	$	129,221

Goodwill

The changes to the carrying amount of goodwill for years ended December 31, 2017 and 2016 were as follows (in thousands):


	Goodwill
Balance, January 1, 2016	$	—
Additions (Note 2)		155,725
Adjustments		(132)
Balance, December 31, 2016	$	155,593
Additions		—
Adjustments		—
Balance, December 31, 2017	$	155,593

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Convertible Notes

12 Months Ended

Dec. 31, 2017

Convertible Notes

Convertible Notes

Note 9. Convertible Notes

The components of the convertible notes were as follows (in thousands):


				Carrying Amount
	Interest Rates			December 31,
Debt	December 31, 2017		Maturities	2017		2016
0.375% Convertible Senior Notes due 2018	0.375	%	2018	$	7,393	$	340,916
1.25% Convertible Senior Notes due 2020	1.25	%	2020		16,608		310,565
					24,001		651,481
Less current portion					7,393		—
				$	16,608	$	651,481

Annual maturities of all convertible notes are as follows (in millions):


2018	$	7.7
2019		—
2020		19.1
2021		—
Thereafter		—
	$	26.8

The carrying amount and fair value of our convertible notes were as follows (in thousands):


	December 31,
	2017				2016
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
0.375% Convertible Senior Notes due 2018	$	7,393	$	14,129	$	340,916	$	749,988
1.25% Convertible Senior Notes due 2020		16,608		35,431		310,565		761,300
	$	24,001	$	49,560	$	651,481	$	1,511,288

The fair values of the 0.375% Convertible Senior Notes due 2018 (the “2018 Notes”) and the 1.25% Convertible Senior Notes due 2020 (the “2020 Notes”) are based on data from readily available pricing sources which utilize market observable inputs and other characteristics for similar types of instruments, and, therefore, these convertible senior notes are classified within Level 2 in the fair value hierarchy.

On November 14, 2013, we issued, in a private placement, $375.0 million aggregate principal amount of the 2018 Notes and $375.0 million aggregate principal amount of the 2020 Notes. Entities affiliated with Julian C. Baker, one of our directors and principal stockholders (the “Baker Entities”), purchased $250.0 million aggregate principal amount of the 2018 Notes and $250.0 million aggregate principal amount of the 2020 Notes in this private placement. As of December 31, 2016, the Baker Entities owned $259.0 million and $274.5 million aggregate principal amounts of the 2018 and 2020 Notes, respectively, which were exchanged in 2017 for shares of common stock as described below. The 2018 Notes bear interest at a rate of 0.375% per annum and the 2020 Notes bear interest at a rate of 1.25% per annum, in each case payable semi‑annually in arrears in cash on May 15 and November 15, beginning on May 15, 2014. The 2018 Notes will mature on November 15, 2018 and the 2020 Notes will mature on November 15, 2020, in each case unless earlier purchased or converted. We may not redeem the Notes prior to their relevant scheduled maturity dates.

Prior to May 14, 2014, the 2018 and 2020 Notes were not convertible except in connection with a make-whole fundamental change, as defined in the respective indentures. Beginning on, and including, May 15, 2014, the 2018 and 2020 Notes are convertible prior to the close of business on the business day immediately preceding May 15, 2018, in the case of the 2018 Notes, and May 15, 2020, in the case of the 2020 Notes, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on March 31, 2014 (and only during such calendar quarter), if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price for the 2018 Notes or 2020 Notes, as applicable, on each applicable trading day; (2) during the five business day period after any five consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of 2018 Notes or 2020 Notes, as applicable, for each trading day of the measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate for the 2018 Notes or 2020 Notes, as applicable, on each such trading day; or (3) upon the occurrence of specified corporate events. On or after May 15, 2018, in the case of the 2018 Notes, and May 15, 2020, in the case of the 2020 Notes, until the close of business on the second scheduled trading day immediately preceding the relevant maturity date, the Notes are convertible at any time, regardless of the foregoing circumstances. Upon conversion we will pay or deliver, as the case may be, cash, shares of common stock or a combination of cash and shares of common stock, at our election.

On January 1, 2018, the 2018 and 2020 Notes became convertible through at least March 31, 2018, based on the meeting the conversion criteria related to the sale price of our common stock during the calendar quarter ended December 31, 2017 as described in (1) above. The 2018 Notes will mature in November 2018, and accordingly, are classified in short term liabilities on the consolidated balance sheet at December 31, 2017. The 2020 Notes are reflected in long term liabilities on the consolidated balance sheet at December 31, 2017 as management’s intent is to settle any conversions of the 2020 Notes during this period in shares of our common stock.

The initial conversion rate for the 2018 Notes is 19.3207 shares of common stock per $1,000 principal amount, equivalent to an initial conversion price of approximately $51.76 per share. The initial conversion rate for the 2020 Notes is 19.3207 shares of common stock per $1,000 principal amount, equivalent to an initial conversion price of approximately $51.76 per share. The conversion rate for each series of the 2018 and 2020 Notes will be subject to adjustment for certain events but will not be adjusted for any accrued and unpaid interest. Upon the occurrence of certain fundamental changes, the holders of the 2018 and 2020 Notes may require us to purchase all or a portion of their 2018 and 2020 Notes for cash at a price equal to 100% of the principal amount of the 2018 and 2020 Notes, plus accrued and unpaid interest, including additional interest, if any, to, but excluding, the fundamental change purchase date. In addition, if, and to the extent, a holder elects to convert any 2018 or 2020 Note in connection with a make‑whole fundamental change transaction, as defined in the indenture, we will, under certain circumstances, increase the applicable conversion rate by a number of additional shares of our common stock.

Since the 2018 and 2020 Notes can be settled in cash or common shares or a combination of cash and common shares at our option, we determined the embedded conversion options in the 2018 and 2020 Notes are not required to be separately accounted for as a derivative. However, since the 2018 and 2020 Notes are within the scope of the accounting guidance for cash convertible instruments, we are required to separate the 2018 and 2020 Notes into a liability and equity component. The carrying amount of the liability component is calculated by measuring the fair value of a similar liability that does not have an associated equity component. The carrying amount of the equity component representing the embedded conversion option is determined by deducting the fair value of the liability component from the initial proceeds. The excess of the principal amount of the liability component over its carrying amount is amortized to interest expense over the expected life of a similar liability that does not have an associated equity component using the effective interest method. The equity component is not re‑measured as long as it continues to meet the conditions for equity classification in the accounting guidance for contracts in an entity’s own equity.

The liability component of the 2018 Notes on the date of issuance was estimated at $299.4 million, and accordingly, the equity component on the date of issuance was $75.6 million. The discount on the 2018 Notes is being amortized to interest expense over the term of the 2018 Notes, using the effective interest method. The carrying value of the 2018 Notes was $7.4 million and $340.9 million, respectively, (net of $0.3 million and $34.1 million of debt discount and issuance costs, respectively) at December 31, 2017 and December 31, 2016.

The liability component of the 2020 Notes on the date of issuance was estimated at $274.8 million, and accordingly, the equity component on the date of issuance was $100.2 million. The discount on the 2020 Notes is being amortized to interest expense over the term of the 2020 Notes, using the effective interest method. The carrying value of the 2020 Notes was $16.6 million and $310.6 million, respectively, (net of $2.5 million and $64.2 million debt discount and issuance costs, respectively) at December 31, 2017 and December 31, 2016.

During the year ended December 31, 2017, we entered into separately negotiated agreements with certain holders of the 2018 Notes pursuant to which such holders agreed to exchange a total of $367.2 million in aggregate principal amount of the 2018 Notes for the shares of our common stock into which the 2018 Notes were originally convertible, aggregating 7.1 million shares, an additional 0.1 million of premium shares (equivalent to $12.6 million in value) and $2.0 million in cash. Similarly we entered into separately negotiated agreements with certain holders of the 2020 Notes pursuant to which such holders agreed to exchange a total of $355.6 million in aggregate principal amount of the 2020 Notes for the shares of our common stock into which the 2020 Notes were originally convertible, aggregating 6.9 million shares, an additional 0.2 million of premium shares (equivalent to $26.8 million in value) and $7.0 million in cash. Included in the agreements were those with the Baker Entities, which agreed to exchange $259.0 million in aggregate principal amount of the 2018 Notes and $274.5 million in aggregate principal amount of the 2020 Notes for an aggregate of 10.6 million shares.

Pursuant to the guidance within the ASC 470-20-40-20, we measured the difference between the fair value and carrying value of the liability portion of the 2018 and 2020 Notes which resulted in recording expense related to senior note conversions of $1.4 million related to the 2018 Notes and $5.1 million related to the 2020 Notes. The estimated fair value of the debt component was determined using a valuation model which is subject to judgement. Assumptions used within the valuation model include an estimated credit rating and an estimated market-based cost of debt. These assumptions were used to perform a discounted cash flow analysis on the future interest and principal payments to determine the estimated fair value of the debt at inducement.

In addition, the fair value of the premium shares issued pursuant to these agreements as well as the cash paid in connection with the agreements totaled $48.4 million and is also included within expense related to senior note conversions on the consolidated statement of operations during the year ended December 31, 2017.

Stockholders' Deficit

12 Months Ended

Dec. 31, 2017

Stockholders' Deficit

Stockholders' Deficit

Note 10. Stockholders’ Deficit

Preferred Stock. We are authorized to issue 5,000,000 shares of preferred stock, none of which was outstanding as of December 31, 2017 and 2016. The Board of Directors may determine the rights, preferences and privileges of any preferred stock issued in the future.

Common Stock. We are authorized to issue 400,000,000 shares of common stock.

On September 7, 2017, we completed a public offering of 4,945,000 shares of our authorized but unissued common stock pursuant to an effective shelf registration statement. The underwriter had an option for a period of 30 days to purchase a maximum of 741,750 additional shares of our common stock, which expired unexercised. We sold the shares of common stock to the underwriter at a price of $131.46 per share, resulting in net proceeds, after deducting expenses related to the offering, of approximately $649.4 million.

Stock Compensation Plans. As of December 31, 2017, we had reserved a total of 13,512,446 shares of our common stock for future issuance related to our stock plans as described below.

2010 Stock Incentive Plan. In May 2010 the Board of Directors adopted the 2010 Stock Incentive Plan, which was amended and restated in April 2013 (the “2010 Plan”) for issuance of common stock to employees, non‑employee directors, consultants, and scientific advisors. Options are granted to employees, consultants, and scientific advisors under the 2010 Plan, pursuant to a formula determined by our Board of Directors. All options are exercisable at the fair market value of the stock on the date of grant. Non‑employee director options expire after ten years.

In May 2012, our stockholders approved an increase in the number of shares of common stock reserved for issuance under the 2010 Plan from 12,553,475 to 16,553,475. In May 2013, our stockholders approved an increase in the number of shares of common stock reserved for issuance under the 2010 Plan from 16,553,475 to 21,753,475. In May 2014, our stockholders approved an increase in the number of shares of common stock reserved for issuance under the 2010 Plan from 21,753,475 to 24,753,475. In May 2016, our stockholders approved an increase in the number of shares of common stock reserved for issuance under the 2010 Plan from 24,753,475 to 30,753,475.

Option activity under the 2010 Stock Plan was as follows:


		Shares Subject to
		Outstanding Options
	Shares Available		Weighted Average
	for Grant	Shares	Exercise Price
Balance at December 31, 2016	6,327,138	11,504,572	$	48.40
Options granted	(2,562,773)	2,562,773	$	119.48
Options exercised	—	(2,715,456)	$	30.50
Options cancelled	145,336	(145,336)	$	97.30
Balance at December 31, 2017	3,909,701	11,206,553	$	68.36

In July 2016, we revised the terms of our annual stock option grants to provide that new option grants would generally have a 10-year term and vest over four years, with 25% vesting after one year and the remainder vesting in 36 equal monthly installments. Previously, our option grants generally had 7-year terms and vested over three years, with 33% vesting after one year and the remainder vesting in 24 equal monthly installments.

Options to purchase a total of 7,250,283, 7,995,735 and 8,239,929 shares as of December 31, 2017, 2016 and 2015, respectively, were exercisable and vested. The aggregate intrinsic value of options exercised for the years ended December 31, 2017, 2016 and 2015 were $264.2 million, $137.0 million and $416.3 million, respectively. At December 31, 2017 the aggregate intrinsic value of options outstanding and vested options are $362.8 million and $362.0 million, respectively.

The following table summarizes information about stock options outstanding as of December 31, 2017 for the 2010 Plan:


	Options Outstanding				Options Exercisable
		Weighted Average	Weighted			Weighted
		Remaining	Average			Average
	Number	Contractual Life	Exercise		Number	Exercise
Range of Exercise Prices	Outstanding	(in years)	Price		Exercisable	Price
$2.80 - $17.79	1,460,251	0.94	$	16.13	1,460,251	$	16.13
$17.89 - $18.30	105,542	1.50		18.12	105,542		18.12
$18.32 - $18.32	1,634,218	2.09		18.32	1,634,218		18.32
$18.97 - $64.55	1,605,405	3.16		47.54	1,605,405		47.54
$67.06 - $73.21	1,168,504	4.80		73.09	828,825		73.06
$73.29 - $85.49	1,137,905	8.02		82.88	508,487		82.45
$88.46 - $95.54	198,735	7.72		91.49	81,033		90.38
$95.76 - $95.76	1,161,545	5.75		95.76	539,083		95.76
$101.00 - $109.68	262,613	7.42		106.54	154,362		107.32
$113.64 - $138.52	2,471,835	9.13		120.26	333,077		115.11
	11,206,553				7,250,283

Restricted Stock Units and Performance Stock Units.

In January 2014, we began granting RSUs and PSUs to our employees at the share price on the date of grant. Each RSU represents the right to acquire one share of our common stock. Each RSU granted prior to July 2016 was subject to cliff vesting after three years. In July 2016, we revised the terms of our RSU grants to provide that the awards will vest 25% annually over four years.

Also, in January 2014, Hervé Hoppenot, our President and Chief Executive Officer, was granted a one-time grant of 400,000 RSUs outside of our 2010 Stock Incentive Plan. Vesting of the RSUs will be subject to Mr. Hoppenot’s continued employment on the applicable vesting dates, with one‑sixth of the RSUs vesting at the end of each of the calendar years 2014 through 2019, subject to earlier acceleration of vesting upon the occurrence of certain events in accordance with the terms of his employment agreement. As of December 31, 2017, a total of 200,000 RSUs granted to Mr. Hoppenot vested, leaving 200,000 RSUs outstanding.

We did not grant any PSUs during the years ended December, 31, 2015, 2016 or 2017. We granted a total of 55,326 PSUs during the year ended December 31, 2014. At December 31, 2016, we recognized stock compensation expense for these awards if the performance conditions were deemed probable of achievement at that date. For PSUs, containing performance conditions which were not deemed probable of achievement at December 31, 2016, no stock compensation expense was recognized for these awards. The actual number of shares of our common stock into which each PSU converted was at a multiplier of 100% based on the performance conditions achieved as of December 31, 2016. As of December 31, 2017, all PSUs had vested and were released.

Based on our historical experience of employee turnover, we have assumed an annualized forfeiture rate of 5% for our options, PSUs and RSUs. Under the true-up provisions of the stock compensation guidance, we will record additional expense as the awards vest if the actual forfeiture rate is lower than we estimated, and will record a recovery of prior expense if the actual forfeiture is higher than we estimated.

RSU and PSU award activity under the 2010 Stock Plan was as follows:


		Shares Subject to
	Shares Available	Outstanding Awards
	for Grant	Shares	Grant Date Value
Balance at December 31, 2016	1,146,152	1,246,570	$	82.05
RSUs granted	(427,668)	427,668	$	124.87
RSUs cancelled	50,718	(50,718)	$	90.21
RSUs released	—	(401,484)	$	125.83
PSUs released	—	(43,376)	$	122.16
Balance at December 31, 2017	769,202	1,178,660	$	98.88

Employee Stock Purchase Plan. On May 21, 1997, our stockholders adopted the 1997 Employee Stock Purchase Plan (the “ESPP”). Each regular full‑time and part‑time employee working 20 hours or more per week is eligible to participate after one month of employment. We issued 157,277, 126,648 and 194,453 shares under the ESPP in 2017, 2016 and 2015, respectively. For the years ended December 31, 2017, 2016 and 2015, we recorded stock compensation expense of $3.2 million, $2.4 million and $2.4 million, respectively, as the ESPP is considered compensatory under the FASB stock compensation rules. As of December 31, 2017, 927,233 shares remain available for issuance under the ESPP.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Stock Compensation

12 Months Ended

Dec. 31, 2017

Stock Compensation

Stock Compensation

Note 11. Stock Compensation

We recorded $133.1 million, $96.2 million and $69.9 million, respectively, of stock compensation expense for the years ended December 31, 2017, 2016 and 2015. We utilized the Black-Scholes valuation model for estimating the fair value of the stock options granted, with the following weighted‑average assumptions:


	Employee Stock Options						Employee Stock Purchase Plan
	For the Year Ended						For the Year Ended
	December 31,						December 31,
	2017		2016		2015		2017		2016		2015
Average risk-free interest rates	1.80	%	1.30	%	1.35	%	1.53	%	0.90	%	0.81	%
Average expected life (in years)	5.25		4.99		5.03		0.50		0.50		0.50
Volatility	49	%	50	%	49	%	38	%	48	%	55	%
Weighted-average fair value (in dollars)	53.41		39.35		34.55		19.42		18.82		16.26

The risk‑free interest rate is derived from the U.S. Federal Reserve rate in effect at the time of grant. The expected life calculation is based on the observed and expected time to the exercise of options by our employees based on historical exercise patterns for similar type options. Expected volatility is based on the historical volatility of our common stock over the period commensurate with the expected life of the options. A dividend yield of zero is assumed based on the fact that we have never paid cash dividends and have no present intention to pay cash dividends.

Total compensation cost of options granted but not yet vested, as of December 31, 2017, was $95.2 million, which is expected to be recognized over the weighted average period of 1.6 years. Total compensation cost of RSUs granted but not yet vested, as of December 31, 2017, was $55.9 million, which is expected to be recognized over the weighted average period of 1.4 years.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Taxes

Income Taxes

Note 12. Income Taxes

We are subject to U.S. federal, state and foreign corporate income taxes. The provision for income taxes is based on income (loss) before provision for income taxes as follows (in thousands):


	Year Ended December 31,
	2017		2016		2015
U.S.	$	36,493	$	272,574	$	110,560
Non-U.S.		(348,783)		(165,170)		(103,004)
Income (loss) before income taxes	$	(312,290)	$	107,404	$	7,556

Our provision for income taxes consists of the following (in thousands):


	Year Ended December 31,
	2017		2016		2015
Current:
State	$	486	$	2,700	$	1,025
Foreign		1,171		482		—
		1,657		3,182		1,025
Deferred:
State		(805)		—		—
Foreign		—		—		—
		(805)		—		—
Total provision for income taxes	$	852	$	3,182	$	1,025

A reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes is as follows (in thousands):


	Year Ended December 31,
	2017		2016		2015
Provision (benefit) at U.S. federal statutory rate	$	(109,302)	$	37,591	$	2,645
Unbenefited net operating losses and tax credits		(99,254)		(47,410)		(29,424)
Non-deductible amortization of debt discount		—		—		1,087
Excess tax benefits related to share-based compensation		(81,021)		(29,541)		—
Deferred tax impact of Tax Cuts and Jobs Act of 2017		196,751		—		—
Foreign tax rate differential		86,777		39,975		21,443
Non-deductible officer compensation		6,351		2,061		4,696
Other		550		506		578
Provision for income taxes	$	852	$	3,182	$	1,025

The foreign tax rate differential in the table above reflects the impact of operations in jurisdictions with tax rates that differ from the U.S. federal statutory rate.

Significant components of our deferred tax assets and liabilities are as follows (in thousands):


	December 31,
	2017		2016
Deferred tax assets:
Net operating loss carry forwards	$	259,189	$	481,155
Federal and state research credits		333,311		250,324
Capitalized research and development		37,044		18,618
Deferred revenue and accruals		11,721		9,882
Non-cash compensation		44,647		56,370
Contingent consideration		41,831		32,500
Intangibles, net		94,249		—
Other		25,724		19,533
Total gross deferred tax assets		847,716		868,382
Less valuation allowance for deferred tax assets		(834,783)		(820,233)
Net deferred tax assets	$	12,933	$	48,149

Deferred tax liabilities:
Property and equipment	$	(11,463)	$	(7,761)
Intangibles, net		—		(5,337)
Equity component of 2018 Notes and 2020 Notes		(665)		(35,051)
Total gross deferred tax liabilities		(12,128)		(48,149)
Net deferred income taxes	$	805	$	—

As of December 31, 2017, the Company has NOL carryforwards, research and development credit carryforwards and orphan drug tax credit carryforwards as follows (in thousands):


	Amount		Expiring if not utilized
Net operating loss carryforwards
Federal	$	862,876	2024 through 2037
State		504,535	2024 through 2037
Foreign		420,725	2020 through 2024
Research and development credit carryforwards
Federal		154,135	2018 through 2037
State		21,577	Indefinite
Orphan drug tax credit carryforwards		181,480	2029 through 2037

Our ability to utilize our federal and state NOLs may be limited under Internal Revenue Code Section 382 (“Section 382”). Section 382 imposes annual limitations on the utilization of NOL carryforwards and other tax attributes upon an ownership change. In general terms, an ownership change may result from transactions that increase the aggregate ownership of certain stockholders in our stock by more than 50 percentage points over a testing period (generally three years). We have completed a Section 382 analysis through the year ended December 31, 2017. Based on this analysis, our NOLs and other tax attributes accumulated through 2017 should not be limited under Section 382.

On December 22, 2017, the Tax Cuts and Jobs Act of 2017 was signed into law making significant changes to the Internal Revenue Code. The Act contains numerous provisions impacting corporate taxpayers. Changes include a federal corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system and temporary full expensing of certain business assets. We have recorded provisional tax impacts related to the revaluation of deferred tax assets and liabilities as well as the temporary full expensing of certain business assets in our consolidated financial statements for the year ended December 31, 2017. The ultimate impact may differ from these provisional amounts, due to additional analysis, changes in interpretations and assumptions, and additional regulatory guidance that may be issued. The financial statement impact is expected to be complete when the 2017 U.S. corporate income tax return is filed in 2018.

The valuation allowance for deferred tax assets increased by approximately $14.6 million during the year ended December 31, 2017, increased by approximately $277.3 million during the year ended December 31, 2016 and decreased by approximately $126.2 million during the year ended December 31, 2015. Upon enactment of the Act, the Company remeasured its U.S. deferred tax assets and liabilities at the applicable tax rate of 21%. The remeasurement resulted in a total decrease in these net assets of $197.0 million, which was fully offset by a corresponding valuation allowance reduction.

Valuation allowances require an assessment of both positive and negative evidence when determining whether it is more likely than not that deferred tax assets are recoverable. Such assessment is required on a jurisdiction-by-jurisdiction basis. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible.

Based upon the Company’s analysis of its historical operating results, as well as projections of the Company’s future taxable income (losses) during the periods in which the temporary differences will be recoverable, management believes the uncertainty regarding the realization of its U.S. and Swiss net deferred tax assets requires a full valuation allowance against such net assets as of December 31, 2017. When performing our assessment on projections of future taxable income (losses), we consider factors such as the likelihood of regulatory approval and commercial success of products currently under development, among other factors.

The financial statement recognition of the benefit for a tax position is dependent upon the benefit being more likely than not to be sustainable upon audit by the applicable taxing authority. If this threshold is met, the tax benefit is then measured and recognized at the largest amount that is greater than 50% likely of being realized upon ultimate settlement. If such unrecognized tax benefits were realized and not subject to valuation allowances, we would recognize a tax benefit of $18.0 million. The following table summarizes the gross amounts of unrecognized tax benefits (in thousands):


	Year Ended December 31,
	2017		2016
Balance at beginning of year	$	10,798	$	836
Additions related to prior periods tax positions		2,571		6,740
Reductions related to prior periods tax positions		(821)		—
Additions related to current period tax positions		5,555		2,652
Acquisitions		—		570
Reductions due to lapse of applicable statute of limitations		(81)		—
Balance at end of year	$	18,022	$	10,798

Our policy is to recognize interest and penalties related to uncertain tax positions, if any, as a component of income tax expense. As of December 31, 2017 and 2016, we accrued interest and penalties of $0.3 million. Due to NOL and tax credit carry forwards that remain unutilized, U.S. federal and state income tax returns remain subject to examination for three years after utilization of that year’s NOL carryforward. The earliest year which generated an NOL included in our current NOL carryforward is 2004 for U.S. federal tax purposes. All tax years for our foreign subsidiaries are open to audit in their respective jurisdictions.

Net Income (Loss) Per Share

12 Months Ended

Dec. 31, 2017

Net Income (Loss) Per Share

Net Income (Loss) Per Share

Note 13. Net Income (Loss) Per Share

Our basic net income (loss) per share is computed by dividing the net income (loss) by the number of weighted average common shares outstanding during the period. Our diluted net income (loss) per share is computed by dividing net income (loss) by the weighted average common shares outstanding during the period assuming potentially dilutive common shares of stock options, RSUs and common shares issuable upon conversion of the 2018 Notes and 2020 Notes using the if-converted method. Common shares issuable upon conversion of the 2018 Notes and 2020 Notes were excluded from the diluted net income (loss) per share computation for all periods presented as their share effect was anti-dilutive.

Net income (loss) per share was calculated as follows for the periods indicated below:


	Year Ended
	December 31,
(in thousands, except per share data)	2017		2016		2015
Basic Net Income (Loss) Per Share
Basic net income (loss)	$	(313,142)	$	104,222	$	6,531
Weighted average common shares outstanding		204,580		187,873		179,601

Basic net income (loss) per share	$	(1.53)	$	0.55	$	0.04
				0		0
Diluted Net Income (Loss) Per Share
Diluted net income (loss)	$	(313,142)	$	104,222	$	6,531
Weighted average common shares outstanding		204,580		187,873		179,601

Dilutive stock options and RSUs		—		6,252		7,701

Weighted average shares used to compute diluted net income (loss) per share		204,580		194,125		187,302

Diluted net income (loss) per share	$	(1.53)	$	0.54	$	0.03

The potential common shares that were excluded from the diluted net income (loss) per share computation are as follows:


	2017	2016	2015
Outstanding stock options and awards	12,585,213	2,792,424	494,468
Common shares issuable upon conversion of the 2018 Notes	149,375	7,245,149	7,245,263
Common shares issuable upon conversion of the 2020 Notes	368,939	7,241,284	7,241,361
Total potential common shares excluded from diluted net income (loss) per share computation	13,103,527	17,278,857	14,981,092

Employee Benefit Plans

12 Months Ended

Dec. 31, 2017

Employee Benefit Plans

Employee Benefit Plans

Note 14. Employee Benefit Plans

Defined Contribution Plans

We have a defined contribution plan qualified under Section 401(k) of the Internal Revenue Code covering all domestic employees and defined contribution plans for other Incyte employees in Europe. Employees may contribute a portion of their compensation, which is then matched by us, subject to certain limitations. Defined contribution expense was $8.9 million, $6.6 million and $2.9 million for the years ended December 31, 2017, 2016 and 2015, respectively. Included in the 2017 and 2016 defined contribution expense is $1.0 million and $0.3 million, respectively, of expense related to matching contributions under the European defined contribution plans.

Defined Benefit Pension Plans

In connection with the Acquisition, we assumed a defined benefit pension plan for the former ARIAD employees. In addition, we established another defined benefit pension plan for other Incyte employees in Europe. The pension plans provide benefits to employees upon retirement, death or disability. The assets of the pension plans are held in collective investment accounts represented by the cash surrender value of an insurance policy and are classified as Level 2 within the fair value hierarchy.

The pension plans assumptions reflect the expected investment return and discount rate on plan assets and disability rate probabilities. The benefit obligation at December 31, 2017 for the plans was determined using a discount rate of 0.75%, rate of compensation increase of 2.00% and long-term expected return on plan assets of 0.75%. The 2017 net periodic benefit cost for the plans was determined using a discount rate of 0.75%, rate of compensation increase of 1.50% and long-term expected return on plan assets of 0.75%. The benefit obligation at December 31, 2016 for the plans was determined using a discount rate of 0.75%, rate of compensation increase of 1.50% and long-term expected return on plan assets of 0.75%. The 2016 net periodic benefit cost for the plans was determined using a discount rate of 0.75%, rate of compensation increase of 1.50% and long-term expected return on plan assets of 0.75%.

Summarized information regarding changes in the obligations and plan assets, the funded status and the amounts recorded as of December 31, 2017 and 2016 were as follows (in thousands):


	2017		2016
Benefit obligation, beginning of year	$	23,787	$	—
Benefit obligations acquired / established		—		17,591
Employer service cost		2,836		1,225
Interest cost		190		76
Plan participants' contributions		1,101		536
Actuarial loss		4,514		2,249
Plan change		1,430		—
Benefit payments from fund		2,853		2,548
Expenses paid from assets		(36)		(20)
Translation (gain) loss		909		(418)
Benefit obligation, end of year		37,584		23,787

Fair value of plan assets, beginning of year		16,699		—
Fair value of plan assets acquired / established		—		12,598
Actual return on plan assets		88		100
Employer contributions		2,891		1,323
Plan participants' contributions		1,101		536
Benefit payments from fund		2,853		2,548
Expenses paid from assets		(36)		(20)
Translation (gain) loss		595		(386)
Fair value of plan assets, end of year		24,191		16,699

Unfunded liability, end of year	$	13,393	$	7,088

The accumulated benefit obligation is $33.1 million and $22.6 million as of December 31, 2017 and 2016, respectively. The unfunded liability is reported in other liabilities on the consolidated balance sheet as of December 31, 2017 and 2016.

The net periodic benefit cost for the year ended December 31, 2017 and 2016 was as follows (in thousands):


	2017		2016
Service cost	$	2,836	$	1,225
Interest cost		190		76
Expected return on plan assets		(138)		(59)
Amortization of prior service cost		154		—
Amortization of actuarial losses		141		—
Net periodic benefit cost	$	3,183	$	1,242

Other changes in the plans assets and the benefit obligation that is recognized in accumulated other comprehensive loss for the year ended December 31, 2017 and 2016 were as follows, net of tax (in thousands):


	2017		2016
Pension liability in other comprehensive loss, beginning of year	$	2,750	$	—
Plan change		1,276		506
Net prior service costs		(140)		—
Net loss		4,564		2,244
Pension liability in other comprehensive loss, end of year	$	8,450	$	2,750

The prior service cost for the pension plans that will be amortized from accumulated other comprehensive loss into net periodic benefit cost over the next fiscal year is $0.2 million. The actuarial loss for the pension plans that will be amortized from accumulated other comprehensive loss into net periodic benefit cost over the next fiscal year is $0.3 million.

We expect to contribute a total of $3.2 million to the pension plans in 2018. The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid (in thousands):


2018	$	1,312
2019		1,418
2020		1,496
2021		1,727
2022		1,801
2023-2027		10,435
Total	$	18,189

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies

Commitments and Contingencies

Note 15. Commitments and Contingencies

Rent expense for all leases for the years ended December 31, 2017, 2016 and 2015, was approximately $8.2 million, $5.4 million and $1.3 million, respectively.

As of December 31, 2017, future non‑cancelable minimum payments under operating, direct financing and capital leases were as follows:


Year Ended December 31,	Operating Leases		Capital Lease
		(in millions)		(in millions)
2018	$	11.5	$	0.5
2019		6.2		0.1
2020		2.3		—
2021		0.7		—
2022		0.3		—
Thereafter		0.1		—
Total minimum lease payments	$	21.1	$	0.6

We lease approximately 160,000 square feet of office space in Chadds Ford, Pennsylvania, approximately 100,000 square feet of laboratory and office space in Wilmington, Delaware and approximately 63,000 square feet of office space in Europe and Japan.

We have entered into and may in the future seek to license additional rights relating to technologies or drug development candidates in connection with our drug discovery and development programs. Under these licenses, we may be required to pay upfront fees, milestone payments, and royalties on sales of future products, which are not reflected in the table above.

Segment Information	12 Months Ended
Segment Information	Dec. 31, 2017
Segment Information
Segment Information	Note 16. Segment Information We currently operate in one operating business segment focused on the discovery, development and commercialization of proprietary therapeutics. Our chief operating decision-maker manages the operations of our company as a single operating segment. We do not operate in any material separate lines of business or separate business entities with respect to our products or product development. During the year ended December 31, 2017, total revenues generated by subsidiaries in the United States was $1.5 billion and total revenues generated from subsidiaries in Europe was $66.9 million. During the year ended December 31, 2016, total revenues generated by subsidiaries in the United States was $1.1 billion and total revenues generated from subsidiaries in Europe was $29.6 million. For the year ended December 31, 2017, product revenues, net consisted of $1.1 billion of JAKAFI product revenues, net and $66.9 million of ICLUSIG product revenues, net. For the year ended December 31, 2016, product revenues, net consisted of $852.8 million of JAKAFI product revenues, net and $29.6 million of ICLUSIG product revenues, net. For the year ended December 31, 2015, all revenues were generated in the United States and all product revenues, net were from JAKAFI sales. As of December 31, 2017, property and equipment, net was approximately $252.4 million in the United States and approximately $7.4 million in Europe. As of December 31, 2016, property and equipment, net was approximately $165.0 million in the United States and approximately $2.7 million in Europe.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Interim Consolidated Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2017

Interim Consolidated Financial Information (Unaudited)

Interim Consolidated Financial Information (Unaudited)

Note 17. Interim Consolidated Financial Information (Unaudited)


	Fiscal 2017 Quarter Ended
(in thousands, except per share data)	March 31,		June 30,		September 30,		December 31,
Revenues(1)	$	384,082	$	326,444	$	381,534	$	444,156
Net income (loss)	$	(187,083)	$	(12,484)	$	36,054	$	(149,629)
Basic net income (loss) per share	$	(0.96)	$	(0.06)	$	0.17	$	(0.71)
Diluted net income (loss) per share	$	(0.96)	$	(0.06)	$	0.17	$	(0.71)
Shares used in computation of basic net income (loss) per share		195,260		205,141		206,796		211,125
Shares used in computation of diluted net income (loss) per share		195,260		205,141		212,610		211,125


	Fiscal 2016 Quarter Ended
(in thousands, except per share data)	March 31,		June 30,		September 30,		December 31,
Revenues(2)	$	263,464	$	246,288	$	269,469	$	326,498
Net income	$	24,047	$	34,425	$	36,877	$	8,873
Basic net income per share	$	0.13	$	0.18	$	0.20	$	0.05
Diluted net income per share	$	0.12	$	0.18	$	0.19	$	0.05
Shares used in computation of basic net income per share		187,184		187,682		188,029		188,598
Shares used in computation of diluted net income per share		192,625		193,015		194,265		195,187

(1)

The quarters ended March 31, 2017, June 30, 2017, September 30, 2017 and December 31, 2017 include $264.8 million, $291.7 million, $322.0 million, and $321.8 million, respectively, of product revenues, net, relating to JAKAFI and ICLUSIG. The quarters ended March 31, 2017, June 30, 2017, September 30, 2017 and December 31, 2017 include $29.2 million, $34.8 million, $44.5 million and $52.3 million, respectively, of product royalty revenues related to the sale of JAKAVI and OLUMIANT outside the United States. In November 2009 and December 2009, we entered into collaborative research and license agreements with Novartis and Lilly, respectively. The quarters ended March 31, 2017, June 30, 2017, September 30, 2017 and December 31, 2017 include $90.0 million, $0.0 million, $15.0 million and $70.0 million, respectively, of milestone and contract revenues relating to these agreements.

(2)

The quarter ended March 31, 2016 includes $183.3 million of product revenues, net, relating to JAKAFI. The quarters ended June 30, 2016, September 30, 2016 and December 31, 2016 include $212.1 million, $236.6 million and $250.4 million, respectively, of product revenues, net, relating to JAKAFI and ICLUSIG. The quarters ended March 31, 2016, June 30, 2016, September 30, 2016 and December 31, 2016 include $21.9 million, $26.0 million, $29.6 million and $33.2 million, respectively, of product royalty revenues related to the sale of JAKAVI outside the United States. In November 2009 and December 2009, we entered into collaborative research and license agreements with Novartis and Lilly, respectively. The quarters ended March 31, 2016, June 30, 2016, September 30, 2016 and December 31, 2016 include $58.2 million, $8.2 million, $3.2 million and $42.9 million, respectively, of milestone and contract revenues relating to these agreements.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2017
Subsequent Events
Subsequent Events	Note 18. Subsequent Events In January 2018, we entered into a target discovery, research collaboration and option agreement with Syros Pharmaceuticals, Inc. Under this agreement, Syros will use its proprietary gene control platform to identify novel therapeutic targets with a focus in myeloproliferative neoplasms and we have received options to obtain exclusive worldwide rights to intellectual property resulting from the collaboration for up to seven validated targets. We will have exclusive worldwide rights to develop and commercialize any therapies under the collaboration that modulate those validated targets. We have agreed to pay Syros up to $54.0 million in target selection and option exercise fees should we decide to exercise all of our options under the agreement. For products resulting from the collaboration against each of the seven selected and validated targets, we have agreed to pay up to $50.0 million in potential development and regulatory milestones and up to $65.0 million in potential commercial milestones. Syros is also eligible to receive low single-digit royalties on net sales of products resulting from the collaboration. We also entered into a related stock purchase agreement with Syros. We paid Syros $2.5 million in cash for access to proprietary technology and $7.5 million in cash for research and development services which will be recorded in research and development expense, and $10.0 million for the purchase of common stock at $12.61 per share which will be recorded as a long term investment.

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Organization and Summary of Significant Accounting Policies
Principles of Consolidation	Principles of Consolidation. The consolidated financial statements include the accounts of Incyte Corporation and our wholly owned subsidiaries. All inter-company accounts, transactions, and profits have been eliminated in consolidation.
Acquisitions	Acquisitions. Acquired businesses are accounted for using the acquisition method of accounting, which requires that assets acquired and liabilities assumed be recorded at fair value, with limited exceptions. Any excess of the purchase price over the fair value of the net assets acquired is recorded as goodwill. Transaction costs are expensed as incurred. The operating results of the acquired business are reflected in our consolidated financial statements after the date of acquisition. Acquired in-process research and development (“IPR&D”) is recognized at fair value and initially characterized as an indefinite-lived intangible asset, irrespective of whether the acquired IPR&D has an alternative future use.
Foreign Currency Translation	Foreign Currency Translation. Operations in non-U.S. entities are recorded in the functional currency of each entity. For financial reporting purposes, the functional currency of an entity is determined by a review of the source of an entity's most predominant cash flows. The results of operations for any non-U.S. dollar functional currency entities are translated from functional currencies into U.S. dollars using the average currency rate during each month. Assets and liabilities are translated using currency rates at the end of the period. Adjustments resulting from translating the financial statements of our foreign entities that use their local currency as the functional currency into U.S. dollars are reflected as a component of other comprehensive income (loss). Transaction gains and losses are recorded in interest and other income, net, in the consolidated statements of operations. To date, both the translation gains or losses in other comprehensive income (loss) and the transaction gains or losses in foreign exchange gain (loss) have been immaterial.
Use of Estimates	Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Concentrations of Credit Risk	Concentrations of Credit Risk. Cash, cash equivalents, marketable securities, trade receivables and restricted investments are financial instruments which potentially subject us to concentrations of credit risk. The estimated fair value of financial instruments approximates the carrying value based on available market information. We primarily invest our excess available funds in debt securities and, by policy, limit the amount of credit exposure to any one issuer and to any one type of investment, other than securities issued or guaranteed by the U.S. government and money market funds that meet certain guidelines. Our receivables mainly relate to our product sales of JAKAFI, ICLUSIG and collaborative agreements with pharmaceutical companies. We have not experienced any significant credit losses on cash, cash equivalents, marketable securities, trade receivables or restricted investments to date and do not require collateral on receivables.
Cash and Cash Equivalents	Cash and Cash Equivalents. Cash and cash equivalents are held in banks or in custodial accounts with banks. Cash equivalents are defined as all liquid investments and money market funds with maturity from date of purchase of 90 days or less that are readily convertible into cash.
Marketable Securities-Available-for-Sale	Marketable Securities—Available‑for‑Sale. Available‑for‑sale securities are carried at fair value, based on quoted market prices and observable inputs, with unrealized gains and losses, net of tax, reported as a separate component of stockholders’ equity. We classify marketable securities that are available for use in current operations as current assets on the consolidated balance sheets. Realized gains and losses and declines in value judged to be other than temporary for available‑for‑sale securities are included in “Interest and other income, net.” The cost of securities sold is based on the specific identification method.
Accounts Receivable	Accounts Receivable. As of December 31, 2017 and 2016, we had no allowance for doubtful accounts. We provide an allowance for doubtful accounts based on experience and specifically identified risks. Accounts receivable are carried at fair value and charged off against the allowance for doubtful accounts when we determine that recovery is unlikely and we cease collection efforts.
Inventory	Inventory. Inventories are determined at the lower of cost and net realizable value with cost determined under the specific identification method and may consist of raw materials, work in process and finished goods. JAKAFI raw materials and work‑in‑process inventory is not subject to expiration and the shelf life of finished goods inventory is 36 months from the start of manufacturing of the finished goods. ICLUSIG raw materials and work-in-process inventory is not subject to expiration and finished goods inventory has a shelf life of 24 months from the start of manufacturing of the finished goods. We evaluate for potential excess inventory by analyzing current and future product demand relative to the remaining product shelf life. We build demand forecasts by considering factors such as, but not limited to, overall market potential, market share, market acceptance and patient usage. We classify inventory as current on the consolidated balance sheets when we expect inventory to be consumed for commercial use within the next twelve months. The ICLUSIG inventories were recorded at fair value less costs to sell in connection with the Acquisition, which resulted in a higher cost of ICLUSIG product revenues over a one year period from the acquisition date.
Variable Interest Entities	Variable Interest Entities. We perform an initial and ongoing evaluation of the entities with which we have variable interests, such as equity ownership, in order to identify entities (i) that do not have sufficient equity investment at risk to permit the entity to finance its activities without additional subordinated financial support or (ii) in which the equity investors lack an essential characteristic of a controlling financial interest as variable interest entities (“VIE” or “VIEs”). If an entity is identified as a VIE, we perform an assessment to determine whether we have both (i) the power to direct activities that most significantly impact the VIE’s economic performance and (ii) have the obligation to absorb losses from or the right to receive benefits of the VIE that could potentially be significant to the VIE. If both of these criteria are satisfied, we are identified as the primary beneficiary of the VIE. As of December 31, 2017, there were no entities in which we held a variable interest which we determined to be VIEs.
Long Term Investments	Long Term Investments. Our long term investments consist of investments in common stock of publicly held companies with whom we have entered into collaboration and license agreements. The investments in companies over which we have significant influence, but not controlling interest, are accounted for using the equity method (fair value option). The investments in companies over which we do not have significant influence are accounted for as available-for-sale securities. We classify all of our investments in common stock of publicly held companies with whom we have entered into collaboration and license agreements as long term investments.
Equity Method Investments	Equity Method Investments. In circumstances where we have the ability to exercise significant influence over the operating and financial policies of a company in which we have an investment, the investment is accounted for either (i) under the equity method of accounting or (ii) at fair value by electing the fair value option under U.S. GAAP. In assessing whether we exercise significant influence, we consider the nature and magnitude of our investment, any voting and protective rights we hold, any participation in the governance of the other company, and other relevant factors such as the presence of a collaboration or other business relationship. Under the equity method of accounting, we record within our results of operations our share of income or loss of the investee company. Under the fair value option, our investment is carried at fair value on our consolidated balance sheets as a long term investment and all changes in fair value are reported in our consolidated statements of operations as an unrealized gain (loss) on long term investments.
Property and Equipment	Property and Equipment. Property and equipment is stated at cost, less accumulated depreciation and amortization. Depreciation is recorded using the straight‑line method over the estimated useful lives of the respective assets. Leasehold improvements are amortized over the shorter of the estimated useful life of the assets or lease term. Management continually reviews the estimated useful lives of technologically sensitive equipment and believes that those estimates appropriately reflect the current useful life of our assets. In the event that a currently unknown significantly advanced technology became commercially available, we would re‑evaluate the value and estimated useful lives of our existing equipment, possibly having a material impact on the financial statements.
Lease Accounting	Lease Accounting. We account for operating leases by recording rent expense on a straight‑line basis over the expected life of the lease, commencing on the date we gain possession of leased property. We include tenant improvement allowances and rent holidays received from landlords and the effect of any rent escalation clauses to determine the straight‑line rent expense over the expected life of the lease. Capital leases are reflected as a liability at the inception of the lease based on the present value of the minimum lease payments or, if lower, the fair value of the property. Assets under capital leases are recorded in property and equipment, net on the consolidated balance sheets and depreciated in a manner similar to other property and equipment.	Lease Accounting. We account for operating leases by recording rent expense on a straight‑line basis over the expected life of the lease, commencing on the date we gain possession of leased property. We include tenant improvement allowances and rent holidays received from landlords and the effect of any rent escalation clauses to determine the straight‑line rent expense over the expected life of the lease. Capital leases are reflected as a liability at the inception of the lease based on the present value of the minimum lease payments or, if lower, the fair value of the property. Assets under capital leases are recorded in property and equipment, net on the consolidated balance sheets and depreciated in a manner similar to other property and equipment.
Other Intangible Assets, net	Other Intangible Assets, net. Other intangible assets, net consist of licensed intellectual property rights acquired in business combinations, which are reported at fair value, less accumulated amortization. Intangible assets with finite lives are amortized over their estimated useful lives using the straight-line method.
In-Process Research and Development	In-Process Research and Development. The fair value of in-process research and development (“IPR&D”) acquired through business combinations is capitalized as an indefinite-lived intangible asset until the completion or abandonment of the related research and development activities. When the related research and development is completed, the asset will be assigned a useful life and amortized.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets. Long-lived assets with finite lives are tested for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If indicators of impairment are present, the asset is tested for recoverability by comparing the carrying value of the asset to the related estimated undiscounted future cash flows expected to be derived from the asset. If the expected cash flows are less than the carrying value of the asset, then the asset is considered to be impaired and its carrying value is written down to fair value, based on the related estimated discounted future cash flows. Indefinite-lived intangible assets, including IPR&D, are tested for impairment annually as of October 1 or more frequently if events or changes in circumstances between annual tests indicate that the asset may be impaired. Impairment losses on indefinite-lived intangible assets are recognized based solely on a comparison of the fair value of the asset to its carrying value. Due to the discontinuation of the OPTIC-2L study described in Note 2 below, we considered our indefinite-lived IPR&D asset to be impaired and recorded a $12.0 million impairment charge in research and development expense on the consolidated statements of operations during the third quarter of 2017.	Impairment of Long-Lived Assets. Long-lived assets with finite lives are tested for impairment whenever events or changes in circumstances indicate that the carrying value of an asset may not be recoverable. If indicators of impairment are present, the asset is tested for recoverability by comparing the carrying value of the asset to the related estimated undiscounted future cash flows expected to be derived from the asset. If the expected cash flows are less than the carrying value of the asset, then the asset is considered to be impaired and its carrying value is written down to fair value, based on the related estimated discounted future cash flows. Indefinite-lived intangible assets, including IPR&D, are tested for impairment annually as of October 1 or more frequently if events or changes in circumstances between annual tests indicate that the asset may be impaired. Impairment losses on indefinite-lived intangible assets are recognized based solely on a comparison of the fair value of the asset to its carrying value. Due to the discontinuation of the OPTIC-2L study described in Note 2 below, we considered our indefinite-lived IPR&D asset to be impaired and recorded a $12.0 million impairment charge in research and development expense on the consolidated statements of operations during the third quarter of 2017.
Goodwill	Goodwill. Goodwill is calculated as the difference between the acquisition date fair value of the consideration transferred and the values assigned to the assets acquired and liabilities assumed. Goodwill is not amortized but is tested for impairment at the reporting unit level at least annually as of October 1 or when a triggering event occurs that could indicate a potential impairment by assessing qualitative factors or performing a quantitative analysis in determining whether it is more likely than not that the fair value of net assets are below their carrying amounts. A reporting unit is the same as, or one level below, an operating segment. Our operations are currently comprised of a single, entity wide reporting unit. We completed our most recent annual impairment assessment as of October 1, 2017 and determined that the carrying value of our reporting unit was not impaired.
Income Taxes	Income Taxes. We account for income taxes using the asset and liability approach which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and amounts reportable for income tax purposes. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more-likely-than-not that some portion or all of the deferred tax assets will not be realized. In addition, we follow the guidance related to accounting for uncertainty in income taxes. This guidance creates a single model to address uncertainty in tax positions and clarifies the accounting for income taxes by prescribing the minimum recognition threshold a tax position is required to meet before it is recognized in the financial statements.
Financing Costs Related to Long-term Debt	Financing Costs Related to Long‑term Debt. Costs associated with obtaining long‑term debt are deferred and amortized over the term of the related debt using the effective interest method. Such costs are presented as a direct deduction from the carrying amount of the long-term debt liability, consistent with debt discounts, on the consolidated balance sheets.
Grant Accounting	Grant Accounting. Grant amounts received from government agencies for operations are deferred and are amortized into income over the service period of the grant. Grant amounts received for purchases of capital assets are deferred and amortized into interest and other income, net over the useful life of the related capital assets. Such amounts are recorded in other liabilities on the consolidated balance sheets.
Net Income (Loss) Per Share	Net Income (Loss) Per Share. Our basic and diluted net income (loss) per share is calculated by dividing the net income (loss) by the weighted average number of shares of common stock outstanding during all periods presented. Options to purchase stock, restricted stock units and shares issuable upon the conversion of convertible debt are included in diluted earnings per share calculations, unless the effects are anti‑dilutive.
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss). Accumulated other comprehensive income (loss) consists of realized and unrealized gains or losses on marketable securities that are classified as available-for-sale, a long-term investment classified as available-for-sale, foreign currency translation gains or losses and defined benefit pension obligations.	Accumulated Other Comprehensive Income (Loss). Accumulated other comprehensive income (loss) consists of realized and unrealized gains or losses on marketable securities that are classified as available-for-sale, a long-term investment classified as available-for-sale, foreign currency translation gains or losses and defined benefit pension obligations.
Revenue Recognition	Revenue Recognition. Revenues are recognized when (1) persuasive evidence of an arrangement exists, (2) delivery has occurred or services have been rendered, (3) the price is fixed or determinable and (4) collectability is reasonably assured. Revenues are deferred for fees received before earned or until no further obligations exist. We exercise judgment in determining that collectability is reasonably assured or that services have been delivered in accordance with the arrangement. We assess whether the fee is fixed or determinable based on the payment terms associated with the transaction and whether the sales price is subject to refund or adjustment. We assess collectability based primarily on the customer’s payment history and on the creditworthiness of the customer. Product Revenues Our product revenues consist of U.S. sales of JAKAFI and European sales of ICLUSIG. Product revenues are recognized once we meet all four revenue recognition criteria described above. In November 2011, we began shipping JAKAFI to our customers in the U.S., which include specialty pharmacies and wholesalers. In June 2016, we acquired the right to and began shipping ICLUSIG to our customers in the European Union and certain other jurisdictions (Note 2), which include retail pharmacies, hospital pharmacies and distributors. We recognize revenues for product received by our customers net of allowances for customer credits, including estimated rebates, chargebacks, discounts, returns, distribution service fees, patient assistance programs, and government rebates, such as Medicare Part D coverage gap reimbursements in the U.S. Product shipping and handling costs are included in cost of product revenues. Customer Credits: Our customers are offered various forms of consideration, including allowances, service fees and prompt payment discounts. We expect our customers will earn prompt payment discounts and, therefore, we deduct the full amount of these discounts from total product sales when revenues are recognized. Service fees are also deducted from total product sales as they are earned. Rebates and Discounts: Allowances for rebates include mandated discounts under the Medicaid Drug Rebate Program in the U.S. and mandated discounts in Europe in markets where government-sponsored healthcare systems are the primary payers for healthcare. Rebates are amounts owed after the final dispensing of the product to a benefit plan participant and are based upon contractual agreements or legal requirements with public sector benefit providers. The accrual for rebates is based on statutory discount rates and expected utilization as well as historical data we have accumulated since product launches. Our estimates for expected utilization of rebates are based on data received from our customers. Rebates are generally invoiced and paid in arrears so that the accrual balance consists of an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarters’ unpaid rebates. If actual future rebates vary from estimates, we may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Chargebacks: Chargebacks are discounts that occur when certain contracted customers, which currently consist primarily of group purchasing organizations, Public Health Service institutions, non‑profit clinics, and Federal government entities purchasing via the Federal Supply Schedule, purchase directly from our wholesalers. Contracted customers generally purchase the product at a discounted price. The wholesalers, in turn, charges back to us the difference between the price initially paid by the wholesalers and the discounted price paid by the contracted customers. In addition to actual chargebacks received we maintain an accrual for chargebacks based on the estimated contractual discounts on the inventory levels on hand in our distribution channel. If actual future chargebacks vary from these estimates, we may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Medicare Part D Coverage Gap: Medicare Part D prescription drug benefit mandates manufacturers to fund 50% of the Medicare Part D insurance coverage gap for prescription drugs sold to eligible patients. Our estimates for the expected Medicare Part D coverage gap are based on historical invoices received and in part from data received from our customers. Funding of the coverage gap is generally invoiced and paid in arrears so that the accrual balance consists of an estimate of the amount expected to be incurred for the current quarter’s activity, plus an accrual balance for known prior quarters. If actual future funding varies from estimates, we may need to adjust prior period accruals, which would affect revenue in the period of adjustment. Co‑payment Assistance: Patients who have commercial insurance and meet certain eligibility requirements may receive co‑payment assistance. We accrue a liability for co‑payment assistance based on actual program participation and estimates of program redemption using data provided by third‑party administrators. Product Royalty Revenues Royalty revenues on commercial sales for ruxolitinib (marketed as JAKAVI® outside the United States) by Novartis Pharmaceutical International Ltd. (“Novartis”) are based on net sales of licensed products in licensed territories as provided by Novartis. Royalty revenues on commercial sales for baricitinib (marketed as OLUMIANT) by Eli Lilly and Company (“Lilly”) are based on net sales of licensed products in licensed territories as provided by Lilly. We recognize royalty revenues in the period the sales occur. Cost of Product Revenues Cost of product revenues includes all JAKAFI related product costs as well as ICLUSIG related product costs. The acquired ICLUSIG inventories were recorded at fair value less costs to sell in connection with the Acquisition, and will result in a higher cost of ICLUSIG product revenues over the period in which this inventory is sold, which is expected to be over a one year period from the acquisition date. In addition, cost of product revenues include low single-digit royalties under our collaboration and license agreement to Novartis on all future sales of JAKAFI in the United States. Subsequent to the Acquisition on June 1, 2016, cost of product revenues also includes the amortization of our licensed intellectual property for ICLUSIG using the straight-line method over the estimated useful life of 12.5 years. Contract and License Revenues Under agreements involving multiple deliverables, services and/or rights to use assets that we entered into prior to January 1, 2011, the multiple elements are divided into separate units of accounting when certain criteria are met, including whether the delivered items have stand‑alone value to the customer and whether there is objective and reliable evidence of the fair value of the undelivered items. When separate units of accounting exist, consideration is allocated among the separate elements based on their respective fair values. The determination of fair value of each element is based on objective evidence from historical sales of the individual elements by us to other customers. If such evidence of fair value for each undelivered element of the arrangement does not exist, all revenue from the arrangement is deferred until such time that evidence of fair value for each undelivered element does exist or until all elements of the arrangement are delivered. When elements are specifically tied to a separate earnings process, revenue is recognized when the specific performance obligation tied to the element is completed. When revenues for an element are not specifically tied to a separate earnings process, they are recognized ratably over the term of the agreement. We assess whether a substantive milestone exists at the inception of our agreements. For all milestones within our arrangements that are considered substantive, we recognize revenue upon the achievement of the associated milestone. If a milestone is not considered substantive, we would recognize the applicable milestone payment over the remaining period of performance under the arrangement. As of December 31, 2017, all remaining potential milestones under our collaborative arrangements are considered substantive. On January 1, 2011, updated guidance on the recognition of revenues for agreements with multiple deliverables became effective and applies to any agreements we may enter into on or after January 1, 2011. This updated guidance (i) relates to whether multiple deliverables exist, how the deliverables in a revenue arrangement should be separated and how the consideration should be allocated; (ii) requires companies to allocate revenues in an arrangement using estimated selling prices of deliverables if a vendor does not have vendor‑specific objective evidence or third‑party evidence of selling price; and (iii) eliminates the use of the residual method and requires companies to allocate revenues using the relative selling price method. During the years ended December 31, 2017, 2016 and 2015, we did not enter into any agreements that are subject to this updated guidance. If we enter into an agreement with multiple deliverables after January 1, 2011 or amend existing agreements, this updated guidance could have a material effect on our financial statements. Our collaborations often include contractual milestones, which typically relate to the achievement of pre‑specified development, regulatory and commercialization events. These three categories of milestone events reflect the three stages of the life‑cycle of our drugs, which we describe in more detail in the following paragraphs. The regulatory review and approval process, which includes preclinical testing and clinical trials of each drug candidate, is lengthy, expensive and uncertain. Securing approval by the U.S. Food and Drug Administration (the “FDA”) requires the submission of extensive preclinical and clinical data and supporting information to the FDA for each indication to establish a drug candidate’s safety and efficacy. The approval process takes many years, requires the expenditure of substantial resources, involves post‑marketing surveillance and may involve ongoing requirements for post‑marketing studies. Before commencing clinical investigations of a drug candidate in humans, we must submit an Investigational New Drug application (“IND”), which must be reviewed by the FDA. The steps generally required before a drug may be marketed in the United States include preclinical laboratory tests, animal studies and formulation studies, submission to the FDA of an IND for human clinical testing, performance of adequate and well‑controlled clinical trials in three phases, as described below, to establish the safety and efficacy of the drug for each indication, submission of a new drug application (“NDA”) or biologics license application (“BLA”) to the FDA for review and FDA approval of the NDA or BLA. Similar requirements exist within foreign regulatory agencies as well. The time required satisfying the FDA requirements or similar requirements of foreign regulatory agencies may vary substantially based on the type, complexity and novelty of the product or the targeted disease. Preclinical testing includes laboratory evaluation of product pharmacology, drug metabolism, and toxicity, which includes animal studies, to assess potential safety and efficacy as well as product chemistry, stability, formulation, development, and testing. The results of the preclinical tests, together with manufacturing information and analytical data, are submitted to the FDA as part of an IND. The FDA may raise safety concerns or questions about the conduct of the clinical trials included in the IND, and any of these concerns or questions must be resolved before clinical trials can proceed. We cannot be sure that submission of an IND will result in the FDA allowing clinical trials to commence. Clinical trials involve the administration of the investigational drug or the marketed drug to human subjects under the supervision of qualified investigators and in accordance with good clinical practices regulations covering the protection of human subjects. Clinical trials typically are conducted in three sequential phases, but the phases may overlap or be combined. Phase I usually involves the initial introduction of the investigational drug into healthy volunteers to evaluate its safety, dosage tolerance, absorption, metabolism, distribution and excretion. Phase II usually involves clinical trials in a limited patient population to evaluate dosage tolerance and optimal dosage, identify possible adverse effects and safety risks, and evaluate and gain preliminary evidence of the efficacy of the drug for specific indications. Phase III clinical trials usually further evaluate clinical efficacy and safety by testing the drug in its final form in an expanded patient population, providing statistical evidence of efficacy and safety, and providing an adequate basis for labeling. We cannot guarantee that Phase I, Phase II or Phase III testing will be completed successfully within any specified period of time, if at all. Furthermore, we, the institutional review board for a trial, or the FDA may suspend clinical trials at any time on various grounds, including a finding that the subjects or patients are being exposed to an unacceptable health risk. Generally, the milestone events contained in our collaboration agreements coincide with the progression of our drugs from development, to regulatory approval and then to commercialization. The process of successfully discovering a new development candidate, having it approved and successfully commercialized is highly uncertain. As such, the milestone payments we may earn from our partners involve a significant degree of risk to achieve. Therefore, as a drug candidate progresses through the stages of its life‑cycle, the value of the drug candidate generally increases.
Research and Development Costs	Research and Development Costs. Our policy is to expense research and development costs as incurred. We often contract with clinical research organizations (“CROs”) to facilitate, coordinate and perform agreed upon research and development of a new drug. To ensure that research and development costs are expensed as incurred, we record monthly accruals for clinical trials and preclinical testing costs based on the work performed under the contract. These CRO contracts typically call for the payment of fees for services at the initiation of the contract and/or upon the achievement of certain clinical trial milestones. In the event that we prepay CRO fees, we record the prepayment as a prepaid asset and amortize the asset into research and development expense over the period of time the contracted research and development services are performed. Most professional fees, including project and clinical management, data management, monitoring, and medical writing fees are incurred throughout the contract period. These professional fees are expensed based on their percentage of completion at a particular date. Our CRO contracts generally include pass through fees. Pass through fees include, but are not limited to, regulatory expenses, investigator fees, travel costs, and other miscellaneous costs, including shipping and printing fees. We expense the costs of pass through fees under our CRO contracts as they are incurred, based on the best information available to us at the time. The estimates of the pass through fees incurred are based on the amount of work completed for the clinical trial and are monitored through correspondence with the CROs, internal reviews and a review of contractual terms. The factors utilized to derive the estimates include the number of patients enrolled, duration of the clinical trial, estimated patient attrition, screening rate and length of the dosing regimen. CRO fees incurred to set up the clinical trial are expensed during the setup period. Under our clinical trial collaboration agreements we may be reimbursed for certain development costs incurred. Such costs are recorded as a reduction of research and development expense in the period in which the related expense is incurred.
Stock Compensation	Stock Compensation. Share-based payment transactions with employees, which include stock options, restricted stock units (“RSUs”) and performance shares (“PSUs”), are recognized as compensation expense over the requisite service period based on their estimated fair values as well as expected forfeiture rates. The stock compensation process requires significant judgment and the use of estimates, particularly surrounding Black-Scholes assumptions such as stock price volatility over the option term and expected option lives, as well as expected forfeiture rates and the probability of PSUs vesting. The fair value of stock options, which are subject to graded vesting, are recognized as compensation expense over the requisite service period using the accelerated attribution method. The fair value of RSUs that are subject to cliff vesting are recognized as compensation expense over the requisite service period using the straight-line attribution method, and the fair value of RSUs that are subject to graded vesting are recognized as compensation expense over the requisite service period using the accelerated attribution method. The fair value of PSUs are recognized as compensation expense beginning at the time in which the performance conditions are deemed probable of achievement, over the remaining requisite service period. We recorded $133.1 million, $96.2 million and $69.9 million of stock compensation expense for the years ended December 31, 2017, 2016 and 2015, respectively.	Stock Compensation. Share-based payment transactions with employees, which include stock options, restricted stock units (“RSUs”) and performance shares (“PSUs”), are recognized as compensation expense over the requisite service period based on their estimated fair values as well as expected forfeiture rates. The stock compensation process requires significant judgment and the use of estimates, particularly surrounding Black-Scholes assumptions such as stock price volatility over the option term and expected option lives, as well as expected forfeiture rates and the probability of PSUs vesting. The fair value of stock options, which are subject to graded vesting, are recognized as compensation expense over the requisite service period using the accelerated attribution method. The fair value of RSUs that are subject to cliff vesting are recognized as compensation expense over the requisite service period using the straight-line attribution method, and the fair value of RSUs that are subject to graded vesting are recognized as compensation expense over the requisite service period using the accelerated attribution method. The fair value of PSUs are recognized as compensation expense beginning at the time in which the performance conditions are deemed probable of achievement, over the remaining requisite service period. We recorded $133.1 million, $96.2 million and $69.9 million of stock compensation expense for the years ended December 31, 2017, 2016 and 2015, respectively. Acquisition-Related Contingent Consideration. Acquisition-related contingent consideration, which consists of our future royalty and certain potential milestone obligations to ARIAD, is recorded on the acquisition date at the estimated fair value of the obligation, in accordance with the acquisition method of accounting. The fair value measurement is based on significant inputs that are unobservable in the market and thus represents a Level 3 measurement. The fair value of the acquisition-related contingent consideration is remeasured each reporting period, with changes in fair value recorded in the consolidated statements of operations.
Acquisition-Related Contingent Consideration	Acquisition-Related Contingent Consideration. Acquisition-related contingent consideration, which consists of our future royalty and certain potential milestone obligations to ARIAD, is recorded on the acquisition date at the estimated fair value of the obligation, in accordance with the acquisition method of accounting. The fair value measurement is based on significant inputs that are unobservable in the market and thus represents a Level 3 measurement. The fair value of the acquisition-related contingent consideration is remeasured each reporting period, with changes in fair value recorded in the consolidated statements of operations.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers,” which will replace numerous requirements in U.S. GAAP, including industry-specific requirements. This guidance provides a five step model to be applied to all contracts with customers, with an underlying principle that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. ASU No. 2014-09 requires extensive quantitative and qualitative disclosures covering the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including disclosures on significant judgments made when applying the guidance. This guidance is effective for annual reporting periods beginning after December 15, 2017 and interim periods therein. We performed an impact assessment which consisted of a review of a representative sample of contracts, discussions with key stakeholders, and a cataloging of potential impacts on our financial statements, accounting policies, financial controls, and operations. The guidance will not have a material impact on our revenue recognition practices for product and royalty revenues. The adoption of ASU 2014-09 will have primarily two impacts on our future milestone and contract revenues generated by our collaborative research and license agreements: (i)Changes in the model for distinct licenses of functional intellectual property which may result in a timing difference of revenue recognition. Whereas revenue from these arrangements was previously recognized over a period of time pursuant to revenue recognition guidance that was in place for our arrangements at the time such arrangements commenced, revenue from new arrangements we enter into may now be recognized at a point in time under the new guidance. (ii)Assessments of milestone payments, which are linked to events that are in our control, will result in variable consideration that may be recognized at an earlier point in time under the new guidance, when it is probable that the milestone will be achieved without a significant future reversal of cumulative revenue expected. We completed our assessment of the impact of this guidance with the cumulative effect of initially applying the standard to be recognized at the date of initial application in retained earnings (also referred to as a “modified retrospective” adoption methodology). The impact under this methodology to our previously reported revenues is insignificant in the periods reported, with no effect to reported revenues in the fiscal year ended December 31, 2017. We will adopt the new standard effective for the fiscal period beginning January 1, 2018, and will report new disclosures required by this guidance within our Form 10-Q for the interim period ending March 31, 2018. Although the adoption of this new standard is anticipated to have an immaterial impact on our revenues and net income on an ongoing basis, we have implemented a controls process to identify and evaluate new revenue-generating contracts with third-party customers. We continue to monitor additional changes, modifications, clarifications or interpretations being undertaken by the FASB, which may impact our current conclusions. The standard will not impact assets or liabilities reported in our consolidated balance sheet; revenues or expenses within the consolidated statement of operations; cash from or used in operating, financing or investing activities on our consolidated cash flows statement upon adoption. In February 2016, the FASB issued ASU No. 2016-02, “Leases,” that requires lessees to recognize assets and liabilities on the balance sheet for most leases including operating leases. Lessees now classify leases as either finance or operating leases and lessors classify all leases as sales-type, direct financing or operating leases. The statement of operations presentation and expense recognition for lessees for finance leases is similar to that of capital leases under Accounting Standards Codification (“ASC”) 840 with separate interest and amortization expense with higher periodic expense in the earlier periods of a lease. For operating leases, the statement of operations presentation and expense recognition is similar to that of operating leases under ASC 840 with single lease cost recognized on a straight-line basis. This guidance is to be applied using a modified retrospective approach at the beginning of the earliest comparative period presented in the financial statements and is effective for annual periods beginning after December 15, 2018 and interim periods therein. Early adoption is permitted. We are currently analyzing the impact of ASU No. 2016-02 and, at this time, are unable to determine the impact of the new standard, on our consolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18, “Restricted Cash,” which requires entities to show the changes in total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash in the statement of cash flows. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions on the balance sheet. The reconciliation can be presented either on the face of the statement of cash flows or in the notes to the financial statements. The new standard is effective for public business entities for fiscal years beginning after December 15, 2017 and interim periods therein and is to be applied retrospectively. The guidance will be applied for the annual period beginning January 1, 2018 and presentation of reconciliations between cash and cash equivalents, and restricted cash balances will be applied retrospectively within the consolidated statement of cash flows. In January 2017, the FASB issued ASU No. 2017-04, “Intangibles–Goodwill and Other,” which eliminates the requirement to calculate the implied fair value of goodwill to measure a goodwill impairment charge. Under the new standard, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value. The new standard is effective for public business entities that are SEC filers for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The standard is to be applied on a prospective basis. We are currently analyzing the impact of ASU No. 2017-04 on our consolidated financial statements. In March 2017, the FASB issued ASU No. 2017-07, “Compensation–Retirement Benefits,” which requires the presentation of the service cost component of the net periodic benefit cost in the same income statement line as other employee compensation costs arising from services rendered during the period. In addition, only the service cost component will be eligible for capitalization in assets. Disclosure of the line(s) used to present the other components of net periodic benefit cost, if the components are not presented separately in the income statement, is also required. The new standard is effective for public business entities for fiscal years beginning after December 15, 2017 and interim periods therein. The guidance on the presentation of the components of net periodic benefit cost in the income statement is to be applied retrospectively. The guidance limiting the capitalization of net periodic benefit cost in assets to the service cost component is to be applied prospectively. We are currently analyzing the impact of ASU No. 2017-07 on our consolidated financial statements. In October 2016, the FASB issued ASU No. 2016-16, “Intra-Entity Transfers of Assets Other Than Inventory,” which requires companies to account for the income tax effects of intercompany sales and transfers of assets other than inventory in the period in which the transfer occurs. The new standard is effective for public business entities for annual periods beginning after December 15, 2017 (i.e. 2018 for a calendar-year entity). The guidance will be applied for the annual period beginning January 1, 2018 using a modified retrospective approach with a cumulative catch-up adjustment to opening retained earnings. We elected to adopt ASU No. 2016-16 as of the first quarter of 2017, which required us to reflect any adjustments as of January 1, 2017. The primary impact of adoption was the recognition of a deferred tax asset of $34.9 million related to the excess of the tax basis over the consolidated book value basis in the intellectual property rights that were licensed from the U.S. parent company to our wholly-owned subsidiary in Switzerland during 2015 and a $2.1 million reversal of long-term prepaid taxes. Under previous guidance, companies were prohibited from recognizing an increase in tax basis and any income taxes incurred as a result of a sale or transfer of assets to companies that are part of a consolidated reporting entity. Given the full valuation allowance placed on the additional $34.9 million of deferred tax assets, the recognition upon adoption only required a $2.1 million adjustment to our retained earnings as of January 1, 2017 due to the adjustment of the prepaid tax asset. In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities.” The standard requires several changes including that equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) be measured at fair value with changes in fair value recognized in results of operations. These provisions will not impact the accounting for our investments in debt securities. The new guidance also changes certain disclosure requirements and other aspects of current U.S. GAAP. Amendments are to be applied as a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. The new standard will be effective for us on January 1, 2018. Based on our current investment holdings, the adoption of this standard will result in the reclassification of our investment in Calithera Biosciences, Inc. which is not expected to have a material impact on our financial position or results. In July 2015, the FASB issued ASU No. 2015-11, “Simplifying the Measurement of Inventory,” which requires inventory to be measured at the lower of cost and net realizable value rather than at the lower of cost or market value. The new standard is effective for public business entities for fiscal years beginning after December 15, 2016 and interim periods therein. The guidance is to be applied prospectively. We adopted ASU No. 2015-11 as of the first quarter of 2017 and the adoption had no impact on our consolidated financial statements. In December 2017, the FASB issued Staff Accounting Bulletin No. 118 (“SAB 118”) to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Cuts and Jobs Act of 2017 (the “Act”). In accordance with SAB 118, we have recorded provisional tax impacts related to the revaluation of deferred tax assets and liabilities as well as the temporary full expensing of certain business assets in our consolidated financial statements for the year ended December 31, 2017. The ultimate impact may differ from these provisional amounts, due to additional analysis, changes in interpretations and assumptions, and additional regulatory guidance that may be issued. The financial statement impact is expected to be complete when the 2017 U.S. corporate income tax return is filed in 2018. In January 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income ("GILTI") provisions of the Act. The GILTI provisions impose a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The guidance indicates that either accounting for deferred taxes related to GILTI inclusions or to treat any taxes on GILTI inclusions as period cost are both acceptable methods subject to an accounting policy election. Effective the first quarter of 2018, we have elected to treat any potential GILTI inclusions as a period charge in the future period in which it is incurred, and therefore this guidance had no impact on our consolidated financial statements for the year ended December 31, 2017.	Recent Accounting Pronouncements

Business Combination (Tables)

12 Months Ended

Dec. 31, 2017

Business Combination

Schedule of assets acquired and liabilities assumed


	Acquisition
	Fair Values
Current assets	$	21,363
Property and equipment		850
Restricted cash		432
Intangible assets(a)		283,000
Total identifiable assets		305,645
Current liabilities		(15,538)
Other long term liabilities		(5,226)
Total liabilities assumed		(20,764)
Goodwill(b)		155,593
Total fair value of consideration transferred	$	440,474

Schedule of unaudited pro forma information


	For the Years Ended
	December 31,
	2016		2015
Pro forma revenues	$	1,148,006	$	780,758
Pro forma net income (loss)	$	102,619	$	(69,892)

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2017

Marketable Securities

Summary of marketable securities portfolio

The following is a summary of our marketable security portfolio as of December 31, 2017 and 2016, respectively.


			Net		Net
	Amortized		Unrealized		Unrealized		Estimated
	Cost		Gains		Losses		Fair Value
	(in thousands)
December 31, 2017
Debt securities (corporate and government)	$	271,401	$	—	$	(1,265)	$	270,136

December 31, 2016
Debt securities (corporate and government)	$	156,330	$	—	$	(127)	$	156,203

Schedule of fair value of assets and liabilities measured on recurring basis

The following fair value hierarchy table presents information about each major category of our financial assets measured at fair value on a recurring basis as of December 31, 2017 (in thousands):


	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2017
Cash and cash equivalents	$	899,509	$	—	$	—	$	899,509
Debt securities (corporate and government)		—		270,136		—		270,136
Long term investments (Note 6)		134,356		—		—		134,356
Total assets	$	1,033,865	$	270,136	$	—	$	1,304,001


	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2017
Contingent consideration (Note 2)	$	—	$	—	$	287,000	$	287,000
Total liabilities	$	—	$	—	$	287,000	$	287,000

Schedule of rollforward of Level 3 liabilities

The following is a roll forward of our Level 3 liabilities (in thousands):


	Level 3
Balance at January 1, 2017	$	301,000
Contingent consideration earned during the period but not yet paid		(6,618)
Payments made during the period		(15,086)
Change in fair value of contingent consideration		7,704
Balance at December 31, 2017	$	287,000

Schedule of fair value of assets measured on recurring basis

The following fair value hierarchy table presents information about each major category of our financial assets measured at fair value on a recurring basis as of December 31, 2016 (in thousands):


	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2016
Cash and cash equivalents	$	652,343	$	—	$	—	$	652,343
Debt securities (corporate and government)		—		156,203		—		156,203
Long term investment (Note 6)		31,987		—		—		31,987
Total assets	$	684,330	$	156,203	$	—	$	840,533

Schedule of fair value of liabilities measured on recurring basis


	Fair Value Measurement at Reporting Date Using:
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs		Balance as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2016
Contingent consideration (Note 2)	$	—	$	—	$	301,000	$	301,000
Total liabilities	$	—	$	—	$	301,000	$	301,000

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Concentration of Credit Risk (Tables)

12 Months Ended

Dec. 31, 2017

Concentration of Credit Risk

Schedule of concentration of credit risk related to collaborative partners


	Percentage of Total Milestone and
	Contract Revenues for the
	Years Ended,
	December 31,
	2017		2016		2015
Collaboration Partner A	37	%	40	%	83	%
Collaboration Partner B	63	%	60	%	17	%

Schedule of concentration of credit risk related to specialty pharmacy customers


	Percentage of Total Net
	Product Revenues for the
	Years Ended,
	December 31,
	2017		2016		2015
Customer A	24	%	25	%	28	%
Customer B	15	%	17	%	19	%
Customer C	13	%	13	%	13	%
Customer D	8	%	9	%	9	%

Inventory (Tables)

12 Months Ended

Dec. 31, 2017

Inventory

Schedule of inventory


	December 31,
	2017		2016
	(in thousands)
Raw materials	$	1,062	$	109
Work-in-process		8,615		15,084
Finished goods		4,771		4,106
		14,448		19,299
Inventories-current		6,482		4,106
Inventories-non-current	$	7,966	$	15,193

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property and Equipment

Schedule of property and equipment


	December 31,
	2017		2016
	(in thousands)
Office equipment	$	14,674	$	9,243
Laboratory equipment		48,807		37,203
Computer equipment		51,351		38,184
Land		5,350		4,125
Building and leasehold improvements		214,245		130,734
		334,427		219,489
Less accumulated depreciation and amortization		(74,664)		(51,810)
Property and equipment, net	$	259,763	$	167,679

Intangible assets and goodwill (Tables)

12 Months Ended

Dec. 31, 2017

Intangible Assets and Goodwill

Schedule of intangible assets, net

The components of intangible assets were as follows (in thousands, except for useful life):


				Balance at December 31, 2017					Balance at December 31, 2016
	Weighted-	Gross					Net		Gross				Net
	Average Useful	Carrying			Accumulated		Carrying		Carrying		Accumulated		Carrying
	Lives (Years)	Amount			Amortization		Amount		Amount		Amortization		Amount
Finite-lived intangible assets:
Licensed IP(1)	12.5	$	271,000		$	34,099	$	236,901	$	271,000	$	12,563	$	258,437
Indefinite-lived intangible assets:
Acquired IPR&D(1)	N/A		—			—		—		12,000		—		12,000
		$	271,000		$	34,099	$	236,901	$	283,000	$	12,563	$	270,437

Schedule of estimated aggregate amortization expense

Estimated aggregate amortization expense based on the current carrying value of amortizable intangible assets will be as follows for the years ending December 31 (in thousands):


		2018		2019		2020		2021		2022		Thereafter
Amortization expense	$	21,536	$	21,536	$	21,536	$	21,536	$	21,536	$	129,221

Schedule of changes to carrying amount of goodwill

The changes to the carrying amount of goodwill for years ended December 31, 2017 and 2016 were as follows (in thousands):


	Goodwill
Balance, January 1, 2016	$	—
Additions (Note 2)		155,725
Adjustments		(132)
Balance, December 31, 2016	$	155,593
Additions		—
Adjustments		—
Balance, December 31, 2017	$	155,593

Convertible Notes (Tables)

12 Months Ended

Dec. 31, 2017

Convertible Notes

Schedule of components of convertible notes

The components of the convertible notes were as follows (in thousands):


				Carrying Amount
	Interest Rates			December 31,
Debt	December 31, 2017		Maturities	2017		2016
0.375% Convertible Senior Notes due 2018	0.375	%	2018	$	7,393	$	340,916
1.25% Convertible Senior Notes due 2020	1.25	%	2020		16,608		310,565
					24,001		651,481
Less current portion					7,393		—
				$	16,608	$	651,481

Schedule of annual maturities of convertible notes

Annual maturities of all convertible notes are as follows (in millions):


2018	$	7.7
2019		—
2020		19.1
2021		—
Thereafter		—
	$	26.8

Schedule of carrying amount and fair value of convertible notes

The carrying amount and fair value of our convertible notes were as follows (in thousands):


	December 31,
	2017				2016
	Carrying				Carrying
	Amount		Fair Value		Amount		Fair Value
0.375% Convertible Senior Notes due 2018	$	7,393	$	14,129	$	340,916	$	749,988
1.25% Convertible Senior Notes due 2020		16,608		35,431		310,565		761,300
	$	24,001	$	49,560	$	651,481	$	1,511,288

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 6
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

+ Details

Stockholders' Deficit (Tables)

12 Months Ended

Dec. 31, 2017

Stockholders' Deficit

Schedule of option activity under the 2010 Stock Plan


		Shares Subject to
		Outstanding Options
	Shares Available		Weighted Average
	for Grant	Shares	Exercise Price
Balance at December 31, 2016	6,327,138	11,504,572	$	48.40
Options granted	(2,562,773)	2,562,773	$	119.48
Options exercised	—	(2,715,456)	$	30.50
Options cancelled	145,336	(145,336)	$	97.30
Balance at December 31, 2017	3,909,701	11,206,553	$	68.36

Schedule of stock options outstanding and exercisable by exercise price range


	Options Outstanding				Options Exercisable
		Weighted Average	Weighted			Weighted
		Remaining	Average			Average
	Number	Contractual Life	Exercise		Number	Exercise
Range of Exercise Prices	Outstanding	(in years)	Price		Exercisable	Price
$2.80 - $17.79	1,460,251	0.94	$	16.13	1,460,251	$	16.13
$17.89 - $18.30	105,542	1.50		18.12	105,542		18.12
$18.32 - $18.32	1,634,218	2.09		18.32	1,634,218		18.32
$18.97 - $64.55	1,605,405	3.16		47.54	1,605,405		47.54
$67.06 - $73.21	1,168,504	4.80		73.09	828,825		73.06
$73.29 - $85.49	1,137,905	8.02		82.88	508,487		82.45
$88.46 - $95.54	198,735	7.72		91.49	81,033		90.38
$95.76 - $95.76	1,161,545	5.75		95.76	539,083		95.76
$101.00 - $109.68	262,613	7.42		106.54	154,362		107.32
$113.64 - $138.52	2,471,835	9.13		120.26	333,077		115.11
	11,206,553				7,250,283

Schedule of activity summarized under all stock plans other than options


		Shares Subject to
	Shares Available	Outstanding Awards
	for Grant	Shares	Grant Date Value
Balance at December 31, 2016	1,146,152	1,246,570	$	82.05
RSUs granted	(427,668)	427,668	$	124.87
RSUs cancelled	50,718	(50,718)	$	90.21
RSUs released	—	(401,484)	$	125.83
PSUs released	—	(43,376)	$	122.16
Balance at December 31, 2017	769,202	1,178,660	$	98.88

Stock Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Stock Compensation

Schedule of valuation assumptions used for valuation of fair value of stock compensation granted


	Employee Stock Options						Employee Stock Purchase Plan
	For the Year Ended						For the Year Ended
	December 31,						December 31,
	2017		2016		2015		2017		2016		2015
Average risk-free interest rates	1.80	%	1.30	%	1.35	%	1.53	%	0.90	%	0.81	%
Average expected life (in years)	5.25		4.99		5.03		0.50		0.50		0.50
Volatility	49	%	50	%	49	%	38	%	48	%	55	%
Weighted-average fair value (in dollars)	53.41		39.35		34.55		19.42		18.82		16.26

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Taxes

Income (loss) from operations before income taxes

The provision for income taxes is based on income (loss) before provision for income taxes as follows (in thousands):


	Year Ended December 31,
	2017		2016		2015
U.S.	$	36,493	$	272,574	$	110,560
Non-U.S.		(348,783)		(165,170)		(103,004)
Income (loss) before income taxes	$	(312,290)	$	107,404	$	7,556

Schedule of provision (benefit) for income taxes

Our provision for income taxes consists of the following (in thousands):


	Year Ended December 31,
	2017		2016		2015
Current:
State	$	486	$	2,700	$	1,025
Foreign		1,171		482		—
		1,657		3,182		1,025
Deferred:
State		(805)		—		—
Foreign		—		—		—
		(805)		—		—
Total provision for income taxes	$	852	$	3,182	$	1,025

Schedule of reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes


	Year Ended December 31,
	2017		2016		2015
Current:
State	$	486	$	2,700	$	1,025
Foreign		1,171		482		—
		1,657		3,182		1,025
Deferred:
State		(805)		—		—
Foreign		—		—		—
		(805)		—		—
Total provision for income taxes	$	852	$	3,182	$	1,025

A reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes is as follows (in thousands):


	Year Ended December 31,
	2017		2016		2015
Provision (benefit) at U.S. federal statutory rate	$	(109,302)	$	37,591	$	2,645
Unbenefited net operating losses and tax credits		(99,254)		(47,410)		(29,424)
Non-deductible amortization of debt discount		—		—		1,087
Excess tax benefits related to share-based compensation		(81,021)		(29,541)		—
Deferred tax impact of Tax Cuts and Jobs Act of 2017		196,751		—		—
Foreign tax rate differential		86,777		39,975		21,443
Non-deductible officer compensation		6,351		2,061		4,696
Other		550		506		578
Provision for income taxes	$	852	$	3,182	$	1,025

Schedule of significant components of deferred tax assets and liabilities

Significant components of our deferred tax assets and liabilities are as follows (in thousands):


	December 31,
	2017		2016
Deferred tax assets:
Net operating loss carry forwards	$	259,189	$	481,155
Federal and state research credits		333,311		250,324
Capitalized research and development		37,044		18,618
Deferred revenue and accruals		11,721		9,882
Non-cash compensation		44,647		56,370
Contingent consideration		41,831		32,500
Intangibles, net		94,249		—
Other		25,724		19,533
Total gross deferred tax assets		847,716		868,382
Less valuation allowance for deferred tax assets		(834,783)		(820,233)
Net deferred tax assets	$	12,933	$	48,149

Deferred tax liabilities:
Property and equipment	$	(11,463)	$	(7,761)
Intangibles, net		—		(5,337)
Equity component of 2018 Notes and 2020 Notes		(665)		(35,051)
Total gross deferred tax liabilities		(12,128)		(48,149)
Net deferred income taxes	$	805	$	—

Schedule of operating loss and tax credit carryforwards

As of December 31, 2017, the Company has NOL carryforwards, research and development credit carryforwards and orphan drug tax credit carryforwards as follows (in thousands):


	Amount		Expiring if not utilized
Net operating loss carryforwards
Federal	$	862,876	2024 through 2037
State		504,535	2024 through 2037
Foreign		420,725	2020 through 2024
Research and development credit carryforwards
Federal		154,135	2018 through 2037
State		21,577	Indefinite
Orphan drug tax credit carryforwards		181,480	2029 through 2037

Unrecognized tax benefits

The following table summarizes the gross amounts of unrecognized tax benefits (in thousands):


	Year Ended December 31,
	2017		2016
Balance at beginning of year	$	10,798	$	836
Additions related to prior periods tax positions		2,571		6,740
Reductions related to prior periods tax positions		(821)		—
Additions related to current period tax positions		5,555		2,652
Acquisitions		—		570
Reductions due to lapse of applicable statute of limitations		(81)		—
Balance at end of year	$	18,022	$	10,798

Net loss per share (Tables)

12 Months Ended

Dec. 31, 2017

Net Income (Loss) Per Share

Schedule of calculation of net income (loss) per share


	Year Ended
	December 31,
(in thousands, except per share data)	2017		2016		2015
Basic Net Income (Loss) Per Share
Basic net income (loss)	$	(313,142)	$	104,222	$	6,531
Weighted average common shares outstanding		204,580		187,873		179,601

Basic net income (loss) per share	$	(1.53)	$	0.55	$	0.04
				0		0
Diluted Net Income (Loss) Per Share
Diluted net income (loss)	$	(313,142)	$	104,222	$	6,531
Weighted average common shares outstanding		204,580		187,873		179,601

Dilutive stock options and RSUs		—		6,252		7,701

Weighted average shares used to compute diluted net income (loss) per share		204,580		194,125		187,302

Diluted net income (loss) per share	$	(1.53)	$	0.54	$	0.03

Schedule of antidilutive securities excluded from the computation of earnings per share

The potential common shares that were excluded from the diluted net income (loss) per share computation are as follows:


	2017	2016	2015
Outstanding stock options and awards	12,585,213	2,792,424	494,468
Common shares issuable upon conversion of the 2018 Notes	149,375	7,245,149	7,245,263
Common shares issuable upon conversion of the 2020 Notes	368,939	7,241,284	7,241,361
Total potential common shares excluded from diluted net income (loss) per share computation	13,103,527	17,278,857	14,981,092

Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

Employee Benefit Plans

Schedule of changes in the obligations and plan assets, the funded status and the amounts recorded

Summarized information regarding changes in the obligations and plan assets, the funded status and the amounts recorded as of December 31, 2017 and 2016 were as follows (in thousands):


	2017		2016
Benefit obligation, beginning of year	$	23,787	$	—
Benefit obligations acquired / established		—		17,591
Employer service cost		2,836		1,225
Interest cost		190		76
Plan participants' contributions		1,101		536
Actuarial loss		4,514		2,249
Plan change		1,430		—
Benefit payments from fund		2,853		2,548
Expenses paid from assets		(36)		(20)
Translation (gain) loss		909		(418)
Benefit obligation, end of year		37,584		23,787

Fair value of plan assets, beginning of year		16,699		—
Fair value of plan assets acquired / established		—		12,598
Actual return on plan assets		88		100
Employer contributions		2,891		1,323
Plan participants' contributions		1,101		536
Benefit payments from fund		2,853		2,548
Expenses paid from assets		(36)		(20)
Translation (gain) loss		595		(386)
Fair value of plan assets, end of year		24,191		16,699

Unfunded liability, end of year	$	13,393	$	7,088

Schedule of net periodic benefit cost

The net periodic benefit cost for the year ended December 31, 2017 and 2016 was as follows (in thousands):


	2017		2016
Service cost	$	2,836	$	1,225
Interest cost		190		76
Expected return on plan assets		(138)		(59)
Amortization of prior service cost		154		—
Amortization of actuarial losses		141		—
Net periodic benefit cost	$	3,183	$	1,242

Schedule of changes recognized in other comprehensive income (loss)


	2017		2016
Pension liability in other comprehensive loss, beginning of year	$	2,750	$	—
Plan change		1,276		506
Net prior service costs		(140)		—
Net loss		4,564		2,244
Pension liability in other comprehensive loss, end of year	$	8,450	$	2,750

Schedule of expected benefit payments

The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid (in thousands):


2018	$	1,312
2019		1,418
2020		1,496
2021		1,727
2022		1,801
2023-2027		10,435
Total	$	18,189

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies

Schedule of future non-cancellable minimum payments under operating, direct financing and capital leases


Year Ended December 31,	Operating Leases		Capital Lease
		(in millions)		(in millions)
2018	$	11.5	$	0.5
2019		6.2		0.1
2020		2.3		—
2021		0.7		—
2022		0.3		—
Thereafter		0.1		—
Total minimum lease payments	$	21.1	$	0.6

Interim Consolidated Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Interim Consolidated Financial Information (Unaudited)

Schedule of Interim Consolidated Financial Information

Note 17. Interim Consolidated Financial Information (Unaudited)


	Fiscal 2017 Quarter Ended
(in thousands, except per share data)	March 31,		June 30,		September 30,		December 31,
Revenues(1)	$	384,082	$	326,444	$	381,534	$	444,156
Net income (loss)	$	(187,083)	$	(12,484)	$	36,054	$	(149,629)
Basic net income (loss) per share	$	(0.96)	$	(0.06)	$	0.17	$	(0.71)
Diluted net income (loss) per share	$	(0.96)	$	(0.06)	$	0.17	$	(0.71)
Shares used in computation of basic net income (loss) per share		195,260		205,141		206,796		211,125
Shares used in computation of diluted net income (loss) per share		195,260		205,141		212,610		211,125


	Fiscal 2016 Quarter Ended
(in thousands, except per share data)	March 31,		June 30,		September 30,		December 31,
Revenues(2)	$	263,464	$	246,288	$	269,469	$	326,498
Net income	$	24,047	$	34,425	$	36,877	$	8,873
Basic net income per share	$	0.13	$	0.18	$	0.20	$	0.05
Diluted net income per share	$	0.12	$	0.18	$	0.19	$	0.05
Shares used in computation of basic net income per share		187,184		187,682		188,029		188,598
Shares used in computation of diluted net income per share		192,625		193,015		194,265		195,187

(1)

(2)

Organization and Summary of Significant Accounting Policies (Details) $ in Thousands		3 Months Ended	12 Months Ended
	Jan. 01, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Organization and Business
Number of operating segments \| item			1
Concentrations of Credit Risk
Number of issuer to which company limits the amount of credit exposure other than US Government guaranteed securities \| item			1
Number of financial investment to which company limits the amount of credit exposure other than US Government guaranteed securities \| item			1
Accounts Receivable
Allowance for doubtful accounts			$ 0	$ 0
Impairment of Long-Lived Assets
Write-off of the acquired IPR&D		$ 12,000	$ 12,000
Revenue Recognition
Percentage of Medicare Part D insurance coverage gap mandate to be funded by manufacturers			50.00%
Categories of milestone events, number \| item			3
Number of stages of life-cycle drugs \| item			3
Stock-Based Compensation
Stock compensation expense			$ 133,100	96,200	$ 69,900
Recent Accounting Pronouncements
Deferred tax assets			847,716	868,382
Income tax (benefit) expense			$ 852	$ 3,182	$ 1,025
ASU No. 2016-16
Recent Accounting Pronouncements
Deferred tax assets	$ 34,900
Reversal of long-term prepaid taxes	(2,100)
Income tax (benefit) expense	$ 2,100
JAKAFI
Inventory
Shelf life for finished goods inventory, maximum			36 months
ICLUSIG
Inventory
Shelf life for finished goods inventory, maximum			24 months
ICLUSIG \| Licensed IP
Revenue Recognition
Amortization period			12 years 6 months

Business Combination - Narratives (Details) - ARIAD Pharmaceuticals - USD ($) $ in Millions		12 Months Ended
	Jun. 01, 2016	Dec. 31, 2017	Dec. 31, 2016
Business combinations
Upfront Payment	$ 147.5
Fair value of consideration transferred
Fair value of consideration transferred	440.5
Cash	147.5
Contingent consideration	$ 293.0
Contingent Consideration
Fair value of consideration transferred
Probability of technical success (“PTS”) (as a percent)	25.00%
Projected cash flows period	18 years
Discount rate (as a percent)	10.00%
Minimum
Business combinations
Royalties paid (as a percentage)	32.00%
Maximum
Business combinations
Royalties paid (as a percentage)	50.00%
Potential future oncology development and regulatory approval milestone payments	$ 135.0
Development costs		$ 7.0	$ 7.0

Business Combination - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 01, 2016	Dec. 31, 2017	Dec. 31, 2016
Amounts Recognized
Goodwill		$ 155,593	$ 155,593
Licensed IP
Amounts Recognized
Weighted average useful life		12 years 6 months
ARIAD Pharmaceuticals
Amounts Recognized
Current assets	$ 21,363
Property and equipment	850
Restricted cash	432
Intangible assets	283,000
Total identifiable assets	305,645
Current liabilities	(15,538)
Other long term liabilities	(5,226)
Total liabilities assumed	(20,764)
Goodwill	155,593
Total fair value of consideration transferred	$ 440,474
ARIAD Pharmaceuticals \| Maximum
Amounts Recognized
Development costs		$ 7,000	$ 7,000
ARIAD Pharmaceuticals \| Licensed IP
Amounts Recognized
Discount rate (as a percent)	15.00%
Gross margins (as a percent)	98.00%
Weighted average useful life	12 years 6 months
ARIAD Pharmaceuticals \| Licensed IP \| Minimum
Amounts Recognized
Tax rates (as a percent)	7.80%
ARIAD Pharmaceuticals \| Licensed IP \| Maximum
Amounts Recognized
Tax rates (as a percent)	13.80%
ARIAD Pharmaceuticals \| IPR&D
Amounts Recognized
Probability of technical success (“PTS”) (as a percent)	25.00%
Discount rate (as a percent)	16.00%
Gross margins (as a percent)	98.00%
ARIAD Pharmaceuticals \| IPR&D \| Minimum
Amounts Recognized
Tax rates (as a percent)	7.80%
ARIAD Pharmaceuticals \| IPR&D \| Maximum
Amounts Recognized
Tax rates (as a percent)	13.80%

Business Combination - Pro Forma Impact of Business Combination (Details) - ARIAD Pharmaceuticals - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Unaudited pro forma information
Acquisition-Related Costs		$ 1,600
Revenue of ARIAD	$ 29,600
Net loss of ARIAD	(48,700)
Pro forma revenues		1,148,006	$ 780,758
Pro forma net income (loss)		102,619	(69,892)
Deferred Revenue	$ 0	$ 0	$ 0

Marketable Securities - Marketable securities portfolio (Details) - Debt securities (corporate and government) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Summary of marketable security portfolio
Amortized Cost	$ 271,401	$ 156,330
Net Unrealized Losses	(1,265)	(127)
Estimated Fair Value	$ 270,136	$ 156,203
Minimum
Summary of marketable security portfolio
Contractual maturity dates	12 months
Maximum
Summary of marketable security portfolio
Contractual maturity dates	18 months

Marketable Securities - Fair value on a recurring basis (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Jun. 01, 2016
Fair value of financial instruments
Transfers from Level 1 to Level 2		$ 0
Long term investments		134,356	$ 31,987
Marketable securities realized gains (losses)
Net realized gain (loss) from sale of marketable securities			(200)
ARIAD Pharmaceuticals
Fair value of financial instruments
Contingent consideration				$ 293,000
Rollforward of Level 3 liabilities
Contingent consideration earned during the period but not yet paid		(6,600)
ICLUSIG
Rollforward of Level 3 liabilities
Change in fair value of contingent consideration	$ 24,000
Level 3
Rollforward of Level 3 liabilities
Balance at the beginning of the period		301,000
Contingent consideration earned during the period but not yet paid		(6,618)
Payments made during the period		(15,086)
Change in fair value of contingent consideration		7,704
Balance at the end of the period		287,000	301,000
Recurring
Fair value of financial instruments
Cash and cash equivalents		899,509	652,343
Debt securities (corporate and government)		270,136	156,203
Long term investments		134,356	31,987
Total assets		1,304,001	840,533
Contingent consideration		287,000	301,000
Total liabilities		287,000	301,000
Recurring \| Level 1
Fair value of financial instruments
Cash and cash equivalents		899,509	652,343
Long term investments		134,356	31,987
Total assets		1,033,865	684,330
Recurring \| Level 2
Fair value of financial instruments
Debt securities (corporate and government)		270,136	156,203
Total assets		270,136	156,203
Recurring \| Level 3
Fair value of financial instruments
Contingent consideration		287,000	301,000
Total liabilities		$ 287,000	$ 301,000

Concentration of Credit Risk (Details)	12 Months Ended
Concentration of Credit Risk (Details)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Contract Revenues \| Customer Concentration Risk \| Collaboration Partner A
Concentration of risk
Percentage of concentration risk	37.00%	40.00%	83.00%
Contract Revenues \| Customer Concentration Risk \| Collaboration Partner B
Concentration of risk
Percentage of concentration risk	63.00%	60.00%	17.00%
Net Product Revenues \| Customer Concentration Risk \| Customer A
Concentration of risk
Percentage of concentration risk	24.00%	25.00%	28.00%
Net Product Revenues \| Customer Concentration Risk \| Customer B
Concentration of risk
Percentage of concentration risk	15.00%	17.00%	19.00%
Net Product Revenues \| Customer Concentration Risk \| Customer C
Concentration of risk
Percentage of concentration risk	13.00%	13.00%	13.00%
Net Product Revenues \| Customer Concentration Risk \| Customer D
Concentration of risk
Percentage of concentration risk	8.00%	9.00%	9.00%
Accounts Receivable \| Credit Concentration Risk \| Collaboration Partner A and B
Concentration of risk
Percentage of concentration risk	47.00%	23.00%
Accounts Receivable \| Credit Concentration Risk \| Customer A, B, C and D
Concentration of risk
Percentage of concentration risk	25.00%	41.00%

Inventory (Details) - USD ($) $ in Thousands	12 Months Ended
Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Raw materials	$ 1,062	$ 109
Work-in-process	8,615	15,084
Finished goods	4,771	4,106
Total inventories	14,448	19,299
Inventories - current	6,482	4,106
Inventories - non -current	$ 7,966	15,193
Inventories acquired		$ 4,000
JAKAFI
Shelf life for finished goods inventory, maximum	36 months
ICLUSIG
Shelf life for finished goods inventory, maximum	24 months

License agreements - Novartis (Details) $ in Thousands	1 Months Ended				3 Months Ended								12 Months Ended								98 Months Ended
License agreements - Novartis (Details) $ in Thousands	Apr. 30, 2016 USD ($)	Jan. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Nov. 30, 2009 USD ($) item	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2017 USD ($)
License agreements
Milestone and contract revenues													$ 175,000	$ 112,512	$ 77,857
Product royalty revenues													160,791	110,711	74,821
JAKAVI \| Non-U.S.
License agreements
Product royalty revenues					$ 52,300	$ 44,500	$ 34,800	$ 29,200	$ 33,200	$ 29,600	$ 26,000	$ 21,900
Novartis
License agreements
Upfront and immediate milestone payment to be received under license agreement				$ 210,000
Upfront payment received under license agreement			$ 150,000
Immediate milestone payment received under license agreement		$ 60,000
Number of deliverables under license agreement \| item				2
Reimbursable costs recorded as deferred revenue			$ 10,900
Reimbursable costs included in accounts receivable					1,600				600				1,600	600							$ 1,600
Research and development expenses reimbursed													3,000	700	1,600
Milestone and contract revenues													65,000	45,000	65,000
Product royalties in accounts receivable					47,700				33,300				47,700	33,300							47,700
Novartis \| Pre-specified Events \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				$ 1,200,000
Novartis \| Development Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone																					132,000
Novartis \| Development Milestones \| Phase III
License agreements
Amount recognized and received for the achievement of a predefined milestone																				$ 50,000
Novartis \| Development Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				174,000
Novartis \| Regulatory Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone																					215,000
Novartis \| Regulatory Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				495,000
Novartis \| Commercialization Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone																					60,000
Novartis \| Commercialization Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				$ 500,000
Novartis \| LY3009104 \| Development Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone															5,000	$ 7,000	$ 25,000		$ 15,000
Novartis \| GVHD \| Development Milestones \| Phase III
License agreements
Amount recognized and received for the achievement of a predefined milestone													25,000
Novartis \| GVHD \| Development and Regulatory Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement	$ 75,000
Novartis \| GVHD \| Development and Commercialization Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone														5,000
Novartis \| JAKAFI \| U.S.
License agreements
Royalties payable					$ 50,500				$ 36,800				50,500	36,800	24,400						$ 50,500
Novartis \| JAKAFI \| Regulatory Milestones \| U.S.
License agreements
Amount recognized and received for the achievement of a predefined milestone																			$ 10,000
Novartis \| JAKAVI
License agreements
Product royalty revenues													$ 151,700	110,700	74,800
Novartis \| JAKAVI \| Minimum
License agreements
Royalty payments on future global net sales (as a percent)													12.00%
Novartis \| JAKAVI \| Maximum
License agreements
Royalty payments on future global net sales (as a percent)													14.00%
Novartis \| JAKAVI \| Regulatory Milestones \| Europe
License agreements
Amount recognized and received for the achievement of a predefined milestone														$ 40,000	25,000	60,000		$ 40,000
Novartis \| JAKAVI \| Regulatory Milestones \| JAPAN
License agreements
Amount recognized and received for the achievement of a predefined milestone															15,000	$ 25,000
Novartis \| JAKAVI \| Commercialization Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone													$ 40,000		20,000
Net sales													$ 600,000		$ 300,000

License agreements - Lilly (Details) $ in Thousands	1 Months Ended				12 Months Ended					97 Months Ended
License agreements - Lilly (Details) $ in Thousands	Jan. 31, 2017	Mar. 31, 2016 USD ($)	Jul. 31, 2010	Dec. 31, 2009 USD ($) item	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2017 USD ($)
License agreements
Research and Development Expense					$ 1,326,361	$ 581,861	$ 479,514
Milestone and contract revenues					175,000	112,512	77,857
Product royalty revenues					$ 160,791	110,711	74,821
Eli Lilly
License agreements
Upfront payment received under license agreement				$ 90,000
Associated future global development costs from the initiation of a Phase IIb trial, if elected to co-develop (as a percentage)	30.00%				30.00%
Research and Development Expense					$ 40,800	27,300	36,000
Number of deliverables under license agreement \| item				2
Milestone and contract revenues					110,000	67,500	$ 12,900
Product royalties in accounts receivable					4,600					$ 4,600
Eli Lilly \| Non-U.S.
License agreements
Product royalty revenues					9,100
Eli Lilly \| Phase IIB
License agreements
Associated future global development costs from the initiation of a Phase IIb trial, if elected to co-develop (as a percentage)			30.00%	30.00%
Eli Lilly \| Pre-specified Events \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				$ 665,000
Eli Lilly \| Development Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone					30,000					129,000
Eli Lilly \| Development Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				150,000
Eli Lilly \| Development Milestones \| Phase III
License agreements
Amount recognized and received for the achievement of a predefined milestone								$ 50,000
Eli Lilly \| Development Milestones \| Phase IIA
License agreements
Amount recognized and received for the achievement of a predefined milestone									$ 30,000
Eli Lilly \| Development Milestones \| Phase IIB
License agreements
Amount recognized and received for the achievement of a predefined milestone									$ 19,000
Eli Lilly \| Regulatory Milestones
License agreements
Amount recognized and received for the achievement of a predefined milestone						35,000				$ 135,000
Eli Lilly \| Regulatory Milestones \| JAPAN
License agreements
Amount recognized and received for the achievement of a predefined milestone					15,000
Eli Lilly \| Regulatory Milestones \| Europe
License agreements
Amount recognized and received for the achievement of a predefined milestone					$ 65,000	20,000
Eli Lilly \| Regulatory Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				365,000
Eli Lilly \| Commercialization Milestones \| Maximum
License agreements
Upfront and immediate milestone payment to be received under license agreement				$ 150,000
Royalty payments on future global net sales (as a percent)					20.00%
Eli Lilly \| GVHD
License agreements
Upfront payment received under license agreement		$ 35,000
Additional milestone payment received under license agreement		$ 40,000
Research and development expenses reimbursed						$ 35,000

License agreements - Agenus (Details) $ / shares in Units, $ in Thousands, shares in Millions				1 Months Ended			12 Months Ended
	Feb. 14, 2017 USD ($) $ / shares	Feb. 01, 2017 USD ($) $ / shares shares	Feb. 18, 2015 USD ($)	Feb. 28, 2017 USD ($) item	Nov. 30, 2015 item	Feb. 28, 2015	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
License agreements
Long term investment							$ 134,356	$ 31,987
Research and development expense							1,326,361	581,861	$ 479,514
Unrealized loss on long term investments							(24,275)	(3,261)	(4,581)
Agenus
License agreements
Research and development expense							$ 19,500	17,500	14,400
Number of program targets \| item				4	3
Royalty payments on future global net sales (as a percent)							15.00%
Agenus \| Accrued and other liabilities
License agreements
Accrued and other liabilities							$ 3,200	11,400
Agenus \| Development, Regulatory and Commercialization Milestones \| Minimum
License agreements
Royalty payments on future global net sales (as a percent)							6.00%
Agenus \| Development, Regulatory and Commercialization Milestones \| Maximum
License agreements
Royalty payments on future global net sales (as a percent)							12.00%
Additional milestone payments under the license agreement				$ 510,000
Agenus \| Development Milestones
License agreements
Upfront payment under license agreement							$ 20,000
Agenus
License agreements
Long term investment							$ 57,900	32,000
Shares owned following stock purchase (as a percent)				11.00%		9.00%
Ownership percentage (as a percent)							18.00%
Unrealized loss on long term investments							$ (13,600)	$ (3,300)	(4,600)
Agenus \| Stock purchase agreement
License agreements
Total consideration paid	$ 60,000		$ 60,000
Long term investment							39,500		39,800
Research and development expense							$ 20,500		$ 20,200
Purchase of common stock under Stock Purchase Agreement (in shares ) \| shares		10.0
Purchase price of common stock		$ 60,000
Per share price \| $ / shares	$ 4.40	$ 6.00
Discount for lack of marketability	$ 4,500
Fair value of shares on the issuance date	$ 39,500

License agreements - Hengrui (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2015
License agreements
Research and development expense	$ 1,326,361	$ 581,861	$ 479,514
Hengrui
License agreements
Upfront payment made under license agreement			25,000
Potential milestone payments to be made				$ 770,000
Research and development expense	$ 3,200	$ 9,800	$ 500
Hengrui \| Regulatory Milestones
License agreements
Potential milestone payments to be made				90,000
Hengrui \| Commercialization Milestones
License agreements
Potential milestone payments to be made				530,000
Hengrui \| Clinical Superiority Milestones
License agreements
Potential milestone payments to be made				$ 150,000

License agreements - Mercus (Details) $ / shares in Units, $ in Thousands, shares in Millions		1 Months Ended			12 Months Ended
	Jan. 23, 2017 USD ($) $ / shares	Feb. 28, 2017 USD ($)	Jan. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($)
License agreements
Long term investment				$ 31,987	$ 134,356	$ 31,987
Research and development expense					1,326,361	581,861	$ 479,514
Unrealized Gain (Loss) on Securities					(24,275)	(3,261)	$ (4,581)
Merus
License agreements
Number of independent programs \| item			11
Number of preclinical discovery programs \| item			2
Number of programs under the resulting products are co-funded for development \| item			2
Associated future global development costs , if elected to co-develop (as a percent)			35.00%
Upfront payment under license agreement		$ 120,000
Research and development expense					6,500
Merus \| Accrued and other liabilities
License agreements
Accrued and other liabilities					2,100
Merus \| U.S.
License agreements
Profit sharing (as a percent)			50.00%
Percentage of profit (losses)			50.00%
Merus \| Minimum
License agreements
Royalty payments on future global net sales (as a percent)			6.00%
Merus \| Minimum \| U.S.
License agreements
Royalty payments on future global net sales (as a percent)			6.00%
Merus \| Minimum \| Non-U.S.
License agreements
Royalty payments on future global net sales (as a percent)			6.00%
Merus \| Maximum
License agreements
Number of additional preclinical discovery programs \| item			9
Royalty payments on future global net sales (as a percent)			10.00%
Percentage of reverse royalty			4.00%
Merus \| Maximum \| U.S.
License agreements
Royalty payments on future global net sales (as a percent)			10.00%
Percentage of additional royalties			4.00%
Merus \| Maximum \| Non-U.S.
License agreements
Royalty payments on future global net sales (as a percent)			10.00%
Merus \| Maximum \| Development and Regulatory Milestones
License agreements
Additional milestone payments under the license agreement			$ 100,000
Merus \| Maximum \| Commercialization Milestones
License agreements
Additional milestone payments under the license agreement			$ 250,000
Merus \| Stock purchase agreement
License agreements
Purchase of common stock under Stock Purchase Agreement (in shares ) \| shares				3.2
Purchase price of common stock				$ 80,000		$ 80,000
Per share price \| $ / shares	$ 24.50			$ 25.00		$ 25.00
Standstill period	3 years
Lock-up period	18 months
Percentage of total shares allowed to sell during any 12-month period (as a percent)	33.00%
Percentage of total shares allowed to sell during any three-month period (as a percent)	10.00%
Discount for lack of marketability	$ 5,600
Fair value of shares on the issuance date	72,800
Total consideration paid	$ 80,000
Long term investment					72,800
Research and development expense					7,200
Fair market value of our long term investments					$ 62,100
Ownership percentage (as a percent)					17.00%
Unrealized Gain (Loss) on Securities					$ (10,700)

License agreements - Calithera (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		12 Months Ended
	Jan. 30, 2017	Jan. 01, 2017	Mar. 31, 2017	Jan. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
License agreements
Long term investment					$ 134,356	$ 31,987
Unrealized Gain (Loss) on Securities					(24,275)	(3,261)	$ (4,581)
Research and development expense					1,326,361	$ 581,861	$ 479,514
Calithera
License agreements
Funding of future development costs (as a percent)				70.00%
Upfront payment made under license agreement				$ 45,000
Potential milestone payments to be made with profit sharing in effect				430,000
Potential milestone payments to be made with profit sharing terminated				$ 750,000
Milestone payment made under license agreement			$ 12,000
Research and development expense					23,400
Calithera \| Accrued and other liabilities
License agreements
Accrued and other liabilities					900
Calithera \| U.S.
License agreements
Percentage of profit (losses)				60.00%
Calithera \| Stock purchase agreement
License agreements
Purchase of common stock under Stock Purchase Agreement (in shares )	1,700,000	1,720,430
Purchase price of common stock		$ 8,000
Per share price	$ 6.75	$ 4.65
Fair market value of our long term investments	$ 11,600
Fair value of shares on the issuance date					14,400
Total consideration paid	53,000
Upfront license fees	45,000
Stock purchase price	$ 8,000
Long term investment					$ 11,600
Ownership percentage (as a percent)					5.00%
Research and development expense					$ 41,400
Calithera \| Stock purchase agreement \| Other Comprehensive Income
License agreements
Unrealized Gain (Loss) on Securities					$ 2,800

License agreements - MacroGenics (Details) - MacroGenics $ in Millions	1 Months Ended
	Dec. 31, 2017 USD ($)
License agreements
Upfront payment under license agreement	$ 150.0
Minimum
License agreements
Royalty payments on future global net sales (as a percent)	15.00%
Maximum
License agreements
Royalty payments on future global net sales (as a percent)	24.00%
Development and Regulatory Milestones \| Maximum
License agreements
Additional milestone payments under the license agreement	$ 420.0
Commercialization Milestones \| Maximum
License agreements
Additional milestone payments under the license agreement	$ 330.0

Property and Equipment, net - Property and equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and equipment, net
Property and Equipment, gross	$ 334,427	$ 219,489
Less accumulated depreciation and amortization	(74,664)	(51,810)
Property and Equipment, net	259,763	167,679
Depreciation expense including amortization expense of leasehold improvements	24,600	14,200	$ 11,300
Office Equipment [Member]
Property and equipment, net
Property and Equipment, gross	14,674	9,243
Equipment [Member]
Property and equipment, net
Property and Equipment, gross	48,807	37,203
Computer Equipment [Member]
Property and equipment, net
Property and Equipment, gross	51,351	38,184
Land
Property and equipment, net
Property and Equipment, gross	5,350	4,125
Building And Leasehold Improvements
Property and equipment, net
Property and Equipment, gross	$ 214,245	$ 130,734

Property and equipment, net - Narrative (Details) $ in Millions	1 Months Ended
	Oct. 31, 2017 USD ($) ft²	Mar. 31, 2017 USD ($)	Apr. 30, 2016 USD ($) ft²	Sep. 30, 2016 building agreement
Laboratory and Office Space in Wilmington, Delaware
Property and equipment, net
Square footage \| ft²			190,000
Purchase price of land and office building(s)			$ 81.3
Laboratory and Office Space in Wilmington, Delaware \| Property and Equipment
Property and equipment, net
Purchase price of land and office building(s)			45.9
Laboratory and Office Space in Wilmington, Delaware \| Land
Property and equipment, net
Purchase price of land and office building(s)			3.8
Laboratory and Office Space in Wilmington, Delaware \| Building And Leasehold Improvements
Property and equipment, net
Purchase price of land and office building(s)			$ 31.6
Laboratory and Office Space in Wilmington, Delaware \| Building
Property and equipment, net
Estimated useful life			P40Y
Land and Two Buildings in Wilmington, Delaware \| 1701 Augustine Cutoff, Wilmington, Delaware
Property and equipment, net
Purchase price of land and office building(s)		$ 8.1
Number of agreements \| agreement				2
Number of buildings \| building				2
Land and Two Buildings in Wilmington, Delaware \| 1701 Augustine Cutoff, Wilmington, Delaware \| Land
Property and equipment, net
Purchase price of land and office building(s)		1.2
Land and Two Buildings in Wilmington, Delaware \| 1701 Augustine Cutoff, Wilmington, Delaware \| Building And Leasehold Improvements
Property and equipment, net
Purchase price of land and office building(s)		$ 6.9
Office Building in Wilmington, Delaware \| Building
Property and equipment, net
Square footage \| ft²	154,000
Office building	$ 91.3
Estimated useful life	P40Y

Intangible assets and goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Finite-lived intangible assets:
Accumulated Amortization		$ 34,099	$ 12,563
Intangible Assets, Net
Gross Carrying Amount		271,000	283,000
Net Carrying Amount		236,901	270,437
Write-off of the acquired IPR&D	$ 12,000	12,000
Amortization expense		21,500	12,600
Amortization Expense
2018		21,536
2019		21,536
2020		21,536
2021		21,536
2022		21,536
Thereafter		129,221
Changes to carrying amount of goodwill
Balance at beginning of the period		155,593
Additions			155,725
Adjustments			(132)
Balance at end of the period		$ 155,593	155,593
IPR&D
Indefinite-lived intangible assets:
Net Carrying Amount			12,000
Licensed IP
Intangible assets
Weighted Average Useful Lives (Years)		12 years 6 months
Finite-lived intangible assets:
Gross Carrying Amount		$ 271,000	271,000
Accumulated Amortization		34,099	12,563
Finite-Lived Intangible Assets, Net, Total		$ 236,901	$ 258,437

Convertible Notes - Components and Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Convertible Notes
Convertible senior notes	$ 16,608	$ 651,481
Total debt	26,800
Annual maturities of Convertible Notes
2018	7,700
2020	19,100
Total debt	26,800
Carrying Amount
Convertible Notes
Convertible senior notes	24,001	651,481
Total debt	24,001	651,481
Less current portion	7,393
Long-term debt, noncurrent	16,608	651,481
Annual maturities of Convertible Notes
Total debt	$ 24,001	$ 651,481
Convertible Senior Notes 0.375 Percent Due 2018
Convertible Notes
Interest rate of debt (as a percent)	0.375%	0.375%
Convertible Senior Notes 0.375 Percent Due 2018 \| Carrying Amount
Convertible Notes
Convertible senior notes	$ 7,393	$ 340,916
Convertible Senior Notes 1.25 Percent Due 2020
Convertible Notes
Interest rate of debt (as a percent)	1.25%	1.25%	1.25%
Convertible Senior Notes 1.25 Percent Due 2020 \| Carrying Amount
Convertible Notes
Convertible senior notes	$ 16,608	$ 310,565

Convertible Notes - Carrying Amount and Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Convertible Notes
Convertible senior notes	$ 16,608	$ 651,481
Carrying Amount
Convertible Notes
Convertible senior notes	24,001	651,481
Fair Value
Convertible Notes
Convertible senior notes	$ 49,560	$ 1,511,288
Convertible Senior Notes 0.375 Percent Due 2018
Convertible Notes
Interest rate of debt (as a percent)	0.375%	0.375%
Convertible Senior Notes 0.375 Percent Due 2018 \| Carrying Amount
Convertible Notes
Convertible senior notes	$ 7,393	$ 340,916
Convertible Senior Notes 0.375 Percent Due 2018 \| Fair Value
Convertible Notes
Convertible senior notes	$ 14,129	$ 749,988
Convertible Senior Notes 1.25 Percent Due 2020
Convertible Notes
Interest rate of debt (as a percent)	1.25%	1.25%	1.25%
Convertible Senior Notes 1.25 Percent Due 2020 \| Carrying Amount
Convertible Notes
Convertible senior notes	$ 16,608	$ 310,565
Convertible Senior Notes 1.25 Percent Due 2020 \| Fair Value
Convertible Notes
Convertible senior notes	$ 35,431	$ 761,300

Convertible Notes - Narrative (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Nov. 14, 2013 USD ($)	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 shares
Convertible Notes
Convertible senior notes		$ 16,608	$ 651,481
4.75% Convertible Senior Notes Due 2015
Convertible Notes
Interest rate of debt (as a percent)				4.75%
Common stock issued in exchange of notes (in shares) \| shares				10,352,784
Convertible Senior Notes 0.375 Percent Due 2018 and Convertible Senior Notes 1.25 Percent Due 2020
Convertible Notes
Number of days within 30 consecutive trading days in which the price of the entity's common stock must exceed the conversion price for the notes to be converted	20 days
Number of consecutive trading days during which the closing price of the entity's common stock must exceed the conversion price for at least 20 days in order for the notes to be convertible	30 days
Percentage of the closing sales price of common stock that the conversion price must exceed in order for the notes to be convertible (as a percent)	130.00%
Number of consecutive business days immediately after any five consecutive trading day period during the note measurement period	5 days
Number of consecutive trading days before five consecutive business days during the note measurement period	5 days
Conversion ratio, principal amount, denominator	1,000
Percentage of the trading price to the product of the last reported sale price of the common stock and the conversion rate, maximum (as a percent)	98.00%
Repurchase price as a percentage of principal		100.00%
Fair value of premium stock issued and cash paid		$ 48,400
Convertible Senior Notes 0.375 Percent Due 2018 and Convertible Senior Notes 1.25 Percent Due 2020 \| Director
Convertible Notes
Common stock issued in exchange of notes (in shares) \| shares		10,600,000
Convertible Senior Notes 0.375 Percent Due 2018
Convertible Notes
Interest rate of debt (as a percent)		0.375%	0.375%
Aggregate principal amount of notes	$ 375,000
Conversion ratio, number of shares per principal amount		0.1932070
Conversion ratio, principal amount, denominator		1,000
Conversion price per share (in dollars per share) \| $ / shares		$ 51.76
Liability on notes on the date of issuance	299,400
Equity component in convertible notes	75,600
Carrying value of notes		$ 7,400	$ 340,900
Debt discount and issuance costs		300	$ 34,100
Aggregate principal amount of notes converted		$ 367,200
Common stock issued in exchange of notes (in shares) \| shares		7,201,058	114
Premium stock issued in exchange of notes (in shares) \| shares		100,000
Value of premium shares issued		$ 12,600
Cash used to fund redemption of notes		2,000
Debt exchange expense		1,400
Convertible Senior Notes 0.375 Percent Due 2018 \| Director
Convertible Notes
Aggregate principal amount of notes	250,000
Carrying value of notes		259,000	$ 259,000
Aggregate principal amount of notes converted		$ 259,000
Convertible Senior Notes 1.25 Percent Due 2020
Convertible Notes
Interest rate of debt (as a percent)		1.25%	1.25%	1.25%
Aggregate principal amount of notes	375,000
Conversion ratio, number of shares per principal amount		0.1932070
Conversion ratio, principal amount, denominator		1,000
Conversion price per share (in dollars per share) \| $ / shares		$ 51.76
Liability on notes on the date of issuance	274,800
Equity component in convertible notes	100,200
Carrying value of notes		$ 16,600	$ 310,600
Debt discount and issuance costs		2,500	$ 64,200
Aggregate principal amount of notes converted		$ 355,600
Common stock issued in exchange of notes (in shares) \| shares		7,095,350	77	3,902
Premium stock issued in exchange of notes (in shares) \| shares		200,000
Value of premium shares issued		$ 26,800
Cash used to fund redemption of notes		7,000
Debt exchange expense		5,100
Convertible Senior Notes 1.25 Percent Due 2020 \| Director
Convertible Notes
Aggregate principal amount of notes	$ 250,000
Carrying value of notes		274,500	$ 274,500
Aggregate principal amount of notes converted		$ 274,500

Stockholders' Deficit - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Sep. 07, 2017	Dec. 31, 2017	Dec. 31, 2016
Preferred stock, shares authorized		5,000,000	5,000,000
Preferred stock, shares outstanding		0	0
Common stock, shares authorized		400,000,000	400,000,000
Public issuance of common stock		4,945,000
Net proceeds from sale of stock		$ 649,387
Public Offering
Public issuance of common stock	4,945,000
Per share price	$ 131.46
Net proceeds from sale of stock	$ 649,400
Over-Allotment Option \| Maximum
Underwriter purchase option period	30 days
Shares available for purchase by underwriter (in shares)	741,750

Stockholders' Deficit - Narartive 2 (Details) - shares		1 Months Ended				6 Months Ended	12 Months Ended
Stockholders' Deficit - Narartive 2 (Details) - shares	May 31, 2014	Jul. 31, 2016	May 31, 2016	May 31, 2013	May 31, 2012	Jun. 30, 2016	Dec. 31, 2017
Stock Compensation Plans
Shares reserved for future issuance related to stock plans							13,512,446
Stock Incentive Plan 2010
Stock Compensation Plans
Shares authorized for issuance	24,753,475		30,753,475	21,753,475	16,553,475
Shares authorized for issuance before increase	21,753,475		24,753,475	16,553,475	12,553,475
Stock Options
Stock Compensation Plans
Expiration period		10 years				7 years
Stock Options \| Stock Incentive Plan 2010 \| Non-employee Director
Stock Compensation Plans
Expiration period							10 years

Stockholders' Deficit - Option activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	Jul. 31, 2016	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares Available For Grant
Outstanding at the beginning of the period (in shares)			6,327,138
Options granted (in shares)			(2,562,773)
Options cancelled (in shares)			145,336
Outstanding at the end of the period (in shares)			3,909,701	6,327,138
Shares Subject to Outstanding Options, Shares
Outstanding at the beginning of the period (in shares)			11,504,572
Options granted (in shares)			2,562,773
Options exercised (in shares)			(2,715,456)
Options cancelled (in shares)			(145,336)
Outstanding at the end of the period (in shares)			11,206,553	11,504,572
Shares Subject to Outstanding Options, Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)			$ 48.40
Options granted (in dollars per share)			119.48
Options exercised (in dollars per share)			30.50
Options cancelled (in dollars per share)			97.30
Outstanding at the end of the period (in dollars per share)			$ 68.36	$ 48.40
Termination period	10 years	7 years
Vesting period	4 years	3 years
Stock option, other disclosures
Options exercisable and vested (in shares)			7,250,283	7,995,735	8,239,929
Intrinsic value of options exercised			$ 264.2	$ 137.0	$ 416.3
Intrinsic value of options outstanding			362.8
Intrinsic value of vested options			$ 362.0
Vesting after one year
Shares Subject to Outstanding Options, Weighted Average Exercise Price
Vesting period	1 year	1 year
Vesting Percentage	25.00%	33.00%
Remainder vesting
Shares Subject to Outstanding Options, Weighted Average Exercise Price
Vesting period	36 months	24 months

Stockholders' Deficit - Stock options outstanding (Details)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Options Outstanding
Number Outstanding (in shares) \| shares	11,206,553
Options Exercisable
Number Exercisable (in shares) \| shares	7,250,283
Range of Exercise Prices $2.80 - $17.79
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	$ 2.80
Exercise price, upper range limit (in dollars per share)	$ 17.79
Options Outstanding
Number Outstanding (in shares) \| shares	1,460,251
Weighted Average Remaining Contractual Life	11 months 9 days
Weighted Average Exercise Price (in dollars per share)	$ 16.13
Options Exercisable
Number Exercisable (in shares) \| shares	1,460,251
Weighted Average Exercise Price (in dollars per share)	$ 16.13
Range of Exercise Prices $17.89 - $18.30
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	17.89
Exercise price, upper range limit (in dollars per share)	$ 18.30
Options Outstanding
Number Outstanding (in shares) \| shares	105,542
Weighted Average Remaining Contractual Life	1 year 6 months
Weighted Average Exercise Price (in dollars per share)	$ 18.12
Options Exercisable
Number Exercisable (in shares) \| shares	105,542
Weighted Average Exercise Price (in dollars per share)	$ 18.12
Range of Exercise Prices $18.32 - $18.32
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	18.32
Exercise price, upper range limit (in dollars per share)	$ 18.32
Options Outstanding
Number Outstanding (in shares) \| shares	1,634,218
Weighted Average Remaining Contractual Life	2 years 1 month 2 days
Weighted Average Exercise Price (in dollars per share)	$ 18.32
Options Exercisable
Number Exercisable (in shares) \| shares	1,634,218
Weighted Average Exercise Price (in dollars per share)	$ 18.32
Range of Exercise Prices $18.97 - $64.55
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	18.97
Exercise price, upper range limit (in dollars per share)	$ 64.55
Options Outstanding
Number Outstanding (in shares) \| shares	1,605,405
Weighted Average Remaining Contractual Life	3 years 1 month 28 days
Weighted Average Exercise Price (in dollars per share)	$ 47.54
Options Exercisable
Number Exercisable (in shares) \| shares	1,605,405
Weighted Average Exercise Price (in dollars per share)	$ 47.54
Range of Exercise Prices $67.06 - $73.21
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	67.06
Exercise price, upper range limit (in dollars per share)	$ 73.21
Options Outstanding
Number Outstanding (in shares) \| shares	1,168,504
Weighted Average Remaining Contractual Life	4 years 9 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 73.09
Options Exercisable
Number Exercisable (in shares) \| shares	828,825
Weighted Average Exercise Price (in dollars per share)	$ 73.06
Range of Exercise Prices $73.29 - $85.49
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	73.29
Exercise price, upper range limit (in dollars per share)	$ 85.49
Options Outstanding
Number Outstanding (in shares) \| shares	1,137,905
Weighted Average Remaining Contractual Life	8 years 7 days
Weighted Average Exercise Price (in dollars per share)	$ 82.88
Options Exercisable
Number Exercisable (in shares) \| shares	508,487
Weighted Average Exercise Price (in dollars per share)	$ 82.45
Range of Exercise Prices $88.46 - $95.54
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	88.46
Exercise price, upper range limit (in dollars per share)	$ 95.54
Options Outstanding
Number Outstanding (in shares) \| shares	198,735
Weighted Average Remaining Contractual Life	7 years 8 months 19 days
Weighted Average Exercise Price (in dollars per share)	$ 91.49
Options Exercisable
Number Exercisable (in shares) \| shares	81,033
Weighted Average Exercise Price (in dollars per share)	$ 90.38
Range of Exercise Prices $95.76 - $95.76
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	95.76
Exercise price, upper range limit (in dollars per share)	$ 95.76
Options Outstanding
Number Outstanding (in shares) \| shares	1,161,545
Weighted Average Remaining Contractual Life	5 years 9 months
Weighted Average Exercise Price (in dollars per share)	$ 95.76
Options Exercisable
Number Exercisable (in shares) \| shares	539,083
Weighted Average Exercise Price (in dollars per share)	$ 95.76
Range of Exercise Prices $101.00 - $109.68
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	101.00
Exercise price, upper range limit (in dollars per share)	$ 109.68
Options Outstanding
Number Outstanding (in shares) \| shares	262,613
Weighted Average Remaining Contractual Life	7 years 5 months 1 day
Weighted Average Exercise Price (in dollars per share)	$ 106.54
Options Exercisable
Number Exercisable (in shares) \| shares	154,362
Weighted Average Exercise Price (in dollars per share)	$ 107.32
Range of Exercise Prices $113.64 - $138.52
Stock options outstanding
Exercise price, lower range limit (in dollars per share)	113.64
Exercise price, upper range limit (in dollars per share)	$ 138.52
Options Outstanding
Number Outstanding (in shares) \| shares	2,471,835
Weighted Average Remaining Contractual Life	9 years 1 month 17 days
Weighted Average Exercise Price (in dollars per share)	$ 120.26
Options Exercisable
Number Exercisable (in shares) \| shares	333,077
Weighted Average Exercise Price (in dollars per share)	$ 115.11

Stockholders' Deficit - RSU and PSU Narrative (Details) $ in Millions	1 Months Ended		6 Months Ended	12 Months Ended				48 Months Ended
	Jul. 31, 2016	Jan. 31, 2014 shares	Jun. 30, 2016	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 shares	Dec. 31, 2017 shares
Stock Compensation Plans
Stock compensation expense \| $				$ 133.1	$ 96.2	$ 69.9
Outstanding (in shares)				769,202	1,146,152			769,202
Stock Options
Stock Compensation Plans
Vesting period	4 years		3 years
Assumed annualized forfeiture rate (as a percent)				5.00%
Restricted Stock Units (RSUs)
Stock Compensation Plans
Number of shares awarded for each RSU (in shares)				1
Percentage of units vesting at the end of each calendar year (as a percent)				25.00%
Vesting period			3 years	4 years
Granted (in shares)				427,668
Assumed annualized forfeiture rate (as a percent)				5.00%
Restricted Stock Units (RSUs) \| President And Chief Executive Officer
Stock Compensation Plans
Granted (in shares)		400,000
Number of units vesting at the end of each of the calendar years 2014 through 2019		0.1667
Vested (in shares)								200,000
Outstanding (in shares)				200,000				200,000
Performance Stock Units (PSUs)
Stock Compensation Plans
Multiplier conversion rate of units into common stock (as a percent)					100.00%
Granted (in shares)				0	0	0	55,326
Stock compensation expense \| $					$ 0.0
Assumed annualized forfeiture rate (as a percent)				5.00%

Stockholders' Deficit - RSU and PSU award activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Shares Available For Grant
Shares Available for Grant Beginning Balance (in shares)	1,146,152
Shares Available for Grant Ending Balance (in shares)	769,202	1,146,152
Shares Subject to Outstanding Options, Shares
Outstanding at the beginning of the period (in shares)	1,246,570
Outstanding at the end of the period (in shares)	1,178,660	1,246,570
Shares Subject to Outstanding Options, Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 82.05
Outstanding at the end of the period (in dollars per share)	$ 98.88	$ 82.05
Restricted Stock Units (RSUs)
Shares Available For Grant
Granted (in shares)	(427,668)
Cancelled (in shares)	50,718
Shares Subject to Outstanding Options, Shares
Granted (in shares)	427,668
Cancelled (in shares)	(50,718)
Released (in shares)	(401,484)
Shares Subject to Outstanding Options, Weighted Average Exercise Price
Granted (in dollars per share)	$ 124.87
Cancelled (in dollars per share)	90.21
Released (in dollars per share)	$ 125.83
Performance Stock Units (PSUs)
Shares Subject to Outstanding Options, Shares
Granted (in shares)	0	0	0	55,326
Released (in shares)	(43,376)
Shares Subject to Outstanding Options, Weighted Average Exercise Price
Released (in dollars per share)	$ 122.16

Stockholders' Deficit - Employee Stock Purchase Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Compensation Plans
Number of shares issued	157,277	126,648	194,453
Stock compensation expense	$ 133.1	$ 96.2	$ 69.9
Employee Stock
Stock Compensation Plans
Employment period for eligibility to participate in the plan	1 month
Number of shares issued	157,277	126,648	194,453
Stock compensation expense	$ 3.2	$ 2.4	$ 2.4
Remaining shares available	927,233
Employee Stock \| Minimum
Stock Compensation Plans
Number of employee working hours per week for eligibility to participate in the plan	20 hours

Stock Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock compensation
Stock compensation expense	$ 133.1	$ 96.2	$ 69.9
Weighted-average fair value assumptions
Valuation method	Black-Scholes valuation model
Employee Stock
Stock compensation
Stock compensation expense	$ 3.2	$ 2.4	$ 2.4
Weighted-average fair value assumptions
Average risk-free interest rates (as a percent)	1.53%	0.90%	0.81%
Average expected life (in years)	6 months	6 months	6 months
Volatility (as a percent)	38.00%	48.00%	55.00%
Weighted-average fair value (in dollars per share)	$ 19.42	$ 18.82	$ 16.26
Stock Options
Weighted-average fair value assumptions
Average risk-free interest rates (as a percent)	1.80%	1.30%	1.35%
Average expected life (in years)	5 years 3 months	4 years 11 months 27 days	5 years 11 days
Volatility (as a percent)	49.00%	50.00%	49.00%
Weighted-average fair value (in dollars per share)	$ 53.41	$ 39.35	$ 34.55
Dividend yield (as a percent)	0.00%
Unrecognized compensation
Unrecognized compensation cost for nonvested option (in dollars)	$ 95.2
Vesting period of recognition of the unrecognized compensation cost of nonvested awards	1 year 7 months 6 days
Restricted Stock Units (RSUs)
Unrecognized compensation
Unrecognized compensation cost for nonvested option (in dollars)	$ 55.9
Vesting period of recognition of the unrecognized compensation cost of nonvested awards	1 year 4 months 24 days
Performance Stock Units (PSUs)
Stock compensation
Stock compensation expense		$ 0.0

Income Taxes - Income before provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income (loss) from operations before income taxes
Income (loss) before income taxes	$ (312,290)	$ 107,404	$ 7,556
U.S.
Income (loss) from operations before income taxes
Income (loss) before income taxes	36,493	272,574	110,560
Non-U.S.
Income (loss) from operations before income taxes
Income (loss) before income taxes	$ (348,783)	$ (165,170)	$ (103,004)

Income Taxes - Provision for income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
State	$ 486	$ 2,700	$ 1,025
Foreign	1,171	482
Current provision for income taxes	1,657	3,182	1,025
Deferred:
State	(805)
Deferred provision for income taxes	(805)
Provision (benefit) for income taxes	$ 852	$ 3,182	$ 1,025

Income Taxes - Reconciliation of income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes
Provision (benefit) at U.S. federal statutory rate	$ (109,302)	$ 37,591	$ 2,645
Unbenefited net operating losses and tax credits	(99,254)	(47,410)	(29,424)
Non-deductible amortization of debt discount			1,087
Excess tax benefits related to share-based compensation	(81,021)	(29,541)
Deferred tax impact of Tax Cuts and Jobs Act of 2017	196,751
Foreign tax rate differential	86,777	39,975	21,443
Non-deductible officer compensation	6,351	2,061	4,696
Other	550	506	578
Provision (benefit) for income taxes	852	3,182	$ 1,025
Deferred tax assets:
Net operating loss carry forwards	259,189	481,155
Federal and state research credits	333,311	250,324
Capitalized research and development	37,044	18,618
Deferred revenue and accruals	11,721	9,882
Non-cash compensation	44,647	56,370
Contingent consideration	41,831	32,500
Intangibles, net	94,249
Other	25,724	19,533
Total gross deferred tax assets	847,716	868,382
Less valuation allowance for deferred tax assets	(834,783)	(820,233)
Net deferred tax assets	12,933	48,149
Deferred tax liabilities:
Property and equipment	(11,463)	(7,761)
Intangibles, net		(5,337)
Equity component of 2018 Notes and 2020 Notes	(665)	(35,051)
Total gross deferred tax liabilities	(12,128)	$ (48,149)
Net deferred income taxes	$ 805

Income Taxes - NOL $ in Thousands	Dec. 31, 2017 USD ($)
Federal
Operating Loss Carryforwards
Net operating loss carryforwards	$ 862,876
State
Operating Loss Carryforwards
Net operating loss carryforwards	504,535
Foreign
Operating Loss Carryforwards
Net operating loss carryforwards	$ 420,725

Income Taxes - Tax Credit Carryforwards $ in Thousands	Dec. 31, 2017 USD ($)
Orphan drug tax credit carryforwards
Tax Credit Carryforward
Tax credit carryforward	$ 181,480
Federal \| Research and development
Tax Credit Carryforward
Tax credit carryforward	154,135
State \| Research and development
Tax Credit Carryforward
Tax credit carryforward	$ 21,577

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal corporate tax rate (as a percent)		35.00%
Increase (decrease) in valuation allowance		$ 14,600	$ 277,300	$ (126,200)
Deferred tax impact of Tax Cuts and Jobs Act of 2017		196,751
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at beginning of period	$ 18,022	10,798	836
Additions related to prior periods tax positions		2,571	6,740
Reductions related to prior periods tax positions		(821)
Additions related to current period tax positions		5,555	2,652
Acquisitions			570
Reductions due to lapse of applicable statute of limitations		(81)
Balance at end of period		18,022	10,798	$ 836
Accrued interest and penalties		$ 300	$ 300
Forecast
Federal corporate tax rate (as a percent)	21.00%

Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic Net Income (Loss) Per Share
Net income (loss)	$ (149,629)	$ 36,054	$ (12,484)	$ (187,083)	$ 8,873	$ 36,877	$ 34,425	$ 24,047	$ (313,142)	$ 104,222	$ 6,531
Weighted average common shares outstanding	211,125,000	206,796,000	205,141,000	195,260,000	188,598,000	188,029,000	187,682,000	187,184,000	204,580,000	187,873,000	179,601,000
Basic net income (loss) per share	$ (0.71)	$ 0.17	$ (0.06)	$ (0.96)	$ 0.05	$ 0.20	$ 0.18	$ 0.13	$ (1.53)	$ 0.55	$ 0.04
Diluted Net Income (Loss) Per Share
Diluted net income (loss)									$ (313,142)	$ 104,222	$ 6,531
Weighted average common shares outstanding	211,125,000	206,796,000	205,141,000	195,260,000	188,598,000	188,029,000	187,682,000	187,184,000	204,580,000	187,873,000	179,601,000
Dilutive stock options and RSU’s										6,252,000	7,701,000
Weighted average shares used to compute diluted net income (loss) per share	211,125,000	212,610,000	205,141,000	195,260,000	195,187,000	194,265,000	193,015,000	192,625,000	204,580,000	194,125,000	187,302,000
Diluted net income (loss) per share	$ (0.71)	$ 0.17	$ (0.06)	$ (0.96)	$ 0.05	$ 0.19	$ 0.18	$ 0.12	$ (1.53)	$ 0.54	$ 0.03
Anti-dilutive securities
Potential common shares excluded from diluted net loss per share computation									13,103,527	17,278,857	14,981,092
Stock Options
Anti-dilutive securities
Potential common shares excluded from diluted net loss per share computation									12,585,213	2,792,424	494,468
Convertible Senior Notes 0.375 Percent Due 2018
Anti-dilutive securities
Potential common shares excluded from diluted net loss per share computation									149,375	7,245,149	7,245,263
Convertible Senior Notes 1.25 Percent Due 2020
Anti-dilutive securities
Potential common shares excluded from diluted net loss per share computation									368,939	7,241,284	7,241,361

Employee Benefit Plans - Defined Contribution Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Plan
Defined contribution expense	$ 8.9	$ 6.6	$ 2.9
European defined contribution plans
Defined Contribution Plan
Defined contribution expense	$ 1.0	$ 0.3

Employee Benefit Plans - Defined Benefit Pension Plann (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Benefit obligation assumptions
Discount rate ( as a percentage)	0.75%	0.75%
Rate of compensation increase ( as a percentage)	2.00%	1.50%
Expected return on plan assets (as a percentage)	0.75%	0.75%
Periodic benefit cost assumptions
Discount rate ( as a percentage)	0.75%	0.75%
Rate of compensation increase ( as a percentage)	1.50%	1.50%
Expected return on plan assets (as a percentage)	0.75%	0.75%
Changes in the obligations
Benefit obligation, beginning of the year	$ 23,787
Benefit obligations acquired / established		$ 17,591
Service cost	2,836	1,225
Interest cost	190	76
Plan participants contributions	1,101	536
Actuarial loss	4,514	2,249
Plan change	1,430
Benefit payments from fund	2,853	2,548
Expenses paid from assets	36	20
Translation gain (loss)	909	(418)
Benefit obligation, end of the year	37,584	23,787
Changes in plan assets
Fair value of plan assets, beginning of year	16,699
Fair value of plan assets acquired / established		12,598
Actual return on plan assets	88	100
Employer contributions	2,891	1,323
Plan participants contributions	1,101	536
Benefit payments from fund	2,853	2,548
Expenses paid from assets	36	20
Translation gain (loss)	595	(386)
Fair value of plan assets, end of year	24,191	16,699
Unfunded liability, end of year	13,393	7,088
Accumulated benefit obligation	$ 33,100	$ 22,600

Employee Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Net periodic benefit cost
Service cost	$ 2,836	$ 1,225
Interest cost	190	76
Expected return on plan assets	(138)	(59)
Amortization of prior service cost	154
Amortization of actuarial losses	141
Net periodic benefit cost	$ 3,183	$ 1,242

Employee Benefit Plans - Other changes in the plan assets and benefit obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Other changes recognized in accumulated other comprehensive income (loss)
Pension liability in other comprehensive income (loss), beginning of year	$ 2,750
Plan change	1,276	$ 506
Net prior service cost	(140)
Net loss	4,564	2,244
Pension liability in other comprehensive income (loss), end of year	8,450	$ 2,750
Amortization into next prior service cost over the next fiscal year	200
Amortization into next actuarial loss over the next fiscal year	$ 300

Employee Benefit Plans - Expected benefit payments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Expected benefit payments
2018	$ 1,312
2019	1,418
2020	1,496
2021	1,727
2022	1,801
2023-2027	10,435
Total	18,189
Defined Benefit Pension Plan
Expected employer contributions
Net periodic benefits cost	$ 3,200

Commitments and Contingencies (Details) $ in Millions	12 Months Ended
Commitments and Contingencies (Details) $ in Millions	Dec. 31, 2017 USD ($) ft²	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Rent expense	$ 8.2	$ 5.4	$ 1.3
Future non-cancelable minimum payments under operating leases
2018	11.5
2019	6.2
2020	2.3
2021	0.7
2022	0.3
Thereafter	0.1
Total minimum lease payments	21.1
Future non-cancelable minimum payments under capital leases
2018	0.5
2019	0.1
Total minimum lease payments	$ 0.6
Chadds Ford, Pennsylvania
Office leases
Square footage \| ft²	160,000
Wilmington, Delaware
Office leases
Square footage \| ft²	100,000
Europe and Japan
Office leases
Square footage \| ft²	63,000

Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
Segment Information (Details) $ in Thousands	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments \| item									1
Total revenues	$ 444,156	$ 381,534	$ 326,444	$ 384,082	$ 326,498	$ 269,469	$ 246,288	$ 263,464	$ 1,536,216	$ 1,105,719	$ 753,751
Product revenues, net									1,200,312	882,404	$ 601,015
Property and equipment, net	259,763				167,679				259,763	167,679
JAKAFI
Revenues from External Customers and Long-Lived Assets [Line Items]
Product revenues, net								$ 183,300	1,100,000	852,800
ICLUSIG
Revenues from External Customers and Long-Lived Assets [Line Items]
Product revenues, net									66,900	29,600
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues									1,500,000	1,100,000
Property and equipment, net	252,400				165,000				252,400	165,000
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues									66,900	29,600
Property and equipment, net	$ 7,400				$ 2,700				$ 7,400	$ 2,700

Interim Consolidated Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interim Consolidated Financial Information (Unaudited)
Revenues	$ 444,156	$ 381,534	$ 326,444	$ 384,082	$ 326,498	$ 269,469	$ 246,288	$ 263,464	$ 1,536,216	$ 1,105,719	$ 753,751
Net income (loss)	$ (149,629)	$ 36,054	$ (12,484)	$ (187,083)	$ 8,873	$ 36,877	$ 34,425	$ 24,047	$ (313,142)	$ 104,222	$ 6,531
Basic net income (loss) per share	$ (0.71)	$ 0.17	$ (0.06)	$ (0.96)	$ 0.05	$ 0.20	$ 0.18	$ 0.13	$ (1.53)	$ 0.55	$ 0.04
Diluted net income (loss) per share	$ (0.71)	$ 0.17	$ (0.06)	$ (0.96)	$ 0.05	$ 0.19	$ 0.18	$ 0.12	$ (1.53)	$ 0.54	$ 0.03
Shares used in computation of basic net income (loss) per share	211,125,000	206,796,000	205,141,000	195,260,000	188,598,000	188,029,000	187,682,000	187,184,000	204,580,000	187,873,000	179,601,000
Shares used in computation of diluted net income (loss) per share	211,125,000	212,610,000	205,141,000	195,260,000	195,187,000	194,265,000	193,015,000	192,625,000	204,580,000	194,125,000	187,302,000

Interim Consolidated Financial Information (Unaudited) - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interim Consolidated Financial Information (Unaudited)
Revenues relating to product									$ 1,200,312	$ 882,404	$ 601,015
Revenues relating to product royalty									160,791	110,711	74,821
Revenues relating to collaborative research and license agreement									175,000	112,512	$ 77,857
JAKAFI and ICLUSIG
Interim Consolidated Financial Information (Unaudited)
Revenues relating to product	$ 321,800	$ 322,000	$ 291,700	$ 264,800	$ 250,400	$ 236,600	$ 212,100
JAKAFI
Interim Consolidated Financial Information (Unaudited)
Revenues relating to product								$ 183,300	$ 1,100,000	$ 852,800
JAKAVI \| Non-U.S.
Interim Consolidated Financial Information (Unaudited)
Revenues relating to product royalty	52,300	44,500	34,800	29,200	33,200	29,600	26,000	21,900
Novartis and Eli Lilly
Interim Consolidated Financial Information (Unaudited)
Revenues relating to collaborative research and license agreement	$ 70,000	$ 15,000	$ 0	$ 90,000	$ 42,900	$ 3,200	$ 8,200	$ 58,200

Subsequent Events (Details) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2018 USD ($) item $ / shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Subsequent events
Research and development expense		$ 1,326,361	$ 581,861	$ 479,514
Subsequent Event \| Syros Pharmaceuticals, Inc.
Subsequent events
Number of program targets \| item	7
Upfront payment under license agreement	$ 2,500
Research and development expense	7,500
Subsequent Event \| Syros Pharmaceuticals, Inc. \| Stock purchase agreement
Subsequent events
Total equity investment	$ 10,000
Per share price \| $ / shares	$ 12.61
Maximum \| Subsequent Event \| Syros Pharmaceuticals, Inc.
Subsequent events
Target selection and option exercise fee payment	$ 54,000
Development and Regulatory Milestones \| Maximum \| Subsequent Event \| Syros Pharmaceuticals, Inc.
Subsequent events
Additional milestone payments under the license agreement	50,000
Commercialization Milestones \| Maximum \| Subsequent Event \| Syros Pharmaceuticals, Inc.
Subsequent events
Additional milestone payments under the license agreement	$ 65,000