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.

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.