Regeneron Pharmaceuticals (REGN) 10-K 9 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 01, 2017	Jun. 30, 2016
Entity Information [Line Items]
Entity Registrant Name	REGENERON PHARMACEUTICALS INC
Entity Central Index Key	872,589
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 35,224,000,000
Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		104,169,299
Class A Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		1,911,456

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 535,203	$ 809,102
Marketable securities	503,481	236,121
Accounts receivable - trade, net	1,343,368	1,152,489
Accounts receivable from Sanofi	92,989	153,152
Accounts receivable from Bayer HealthCare	175,263	162,152
Inventories	399,356	238,578
Prepaid expenses and other current assets	130,528	163,501
Total current assets	3,180,188	2,915,095
Marketable securities	864,260	632,162
Property, plant, and equipment, net	2,083,421	1,594,120
Deferred tax assets	825,303	461,945
Other assets	20,294	5,810
Total assets	6,973,466	5,609,132
Current liabilities:
Accounts payable and accrued expenses	879,096	644,112
Capital Lease Obligations	127,274	0
Deferred revenue from Sanofi, current portion	115,267	101,573
Deferred revenue - other, current portion	116,397	51,914
Other current liabilities	3,461	13,563
Total current liabilities	1,241,495	811,162
Deferred revenue from Sanofi	503,474	582,664
Deferred revenue - other	327,298	82,015
Facility lease obligations	351,569	362,919
Other long term liabilities	100,385	115,535
Total liabilities	2,524,221	1,954,295
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred Stock	0	0
Additional paid-in capital	3,029,993	3,099,526
Retained earnings	1,748,222	852,700
Accumulated other comprehensive (loss) income	(12,840)	8,572
Treasury Stock	(316,240)	(306,069)
Total stockholders' equity	4,449,245	3,654,837
Total liabilities and stockholders' equity	6,973,466	5,609,132
Class A Stock
Stockholders' equity:
Common stock	2	2
Total stockholders' equity	2	2
Common Stock
Stockholders' equity:
Common stock	108	106
Total stockholders' equity	$ 108	$ 106

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Liabilities and Equity [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	30,000,000	30,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Treasury stock, shares outstanding (in shares)	3,763,868	3,642,820
Class A Stock
Liabilities and Equity [Abstract]
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	40,000,000	40,000,000
Common Stock, shares issued (in shares)	1,911,456	1,913,776
Common Stock, shares outstanding (in shares)	1,911,456	1,913,776
Common Stock
Liabilities and Equity [Abstract]
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	320,000,000	320,000,000
Common Stock, shares issued (in shares)	107,860,567	106,378,001

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Net product sales	$ 3,338,390	$ 2,689,478	$ 1,750,762
Sanofi collaboration revenue	658,665	758,873	541,299
Bayer collaboration revenue	744,270	580,488	495,555
Other revenue	119,102	74,889	31,941
Total revenues	4,860,427	4,103,728	2,819,557
Expenses:
Research and development	2,052,295	1,620,577	1,271,353
Selling, general, and administrative	1,177,697	838,526	519,267
Cost of goods sold	194,624	241,702	129,030
Cost of collaboration and contract manufacturing	105,070	151,007	75,988
Total expenses	3,529,686	2,851,812	1,995,638
Income from operations	1,330,741	1,251,916	823,919
Other income (expense):
Other income (expense), net	6,269	(12,578)	(25,312)
Interest expense	(7,195)	(14,241)	(37,372)
Total other income (expense)	(926)	(26,819)	(62,684)
Income before income taxes	1,329,815	1,225,097	761,235
Income tax expense	(434,293)	(589,041)	(423,109)
Net income	$ 895,522	$ 636,056	$ 338,126
Net income per share - basic	$ 8.55	$ 6.17	$ 3.36
Net income per share - diluted	$ 7.70	$ 5.52	$ 2.98
Weighted average shares outstanding - basic	104,719	103,061	100,612
Weighted average shares outstanding - diluted	116,367	115,230	113,413
Statements of Comprehensive Income
Net income	$ 895,522	$ 636,056	$ 338,126
Other comprehensive income (loss):
Unrealized (loss) gain on marketable securities, net of tax	(21,412)	(43,679)	53,439
Comprehensive income	$ 874,110	$ 592,377	$ 391,565

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($)	Total	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Common Class A	Common Stock	Warrant
Balance at Dec. 31, 2013	$ 1,964,716,000	$ 2,087,287,000	$ (121,482,000)	$ 0	$ (1,188,000)	$ 2,000	$ 97,000
Balance (shares) at Dec. 31, 2013				0		2,020,000	97,667,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	125,897,000	125,893,000					$ 4,000
Issuance of Common Stock in connection with exercise of stock options (shares)							3,468,000
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(267,584,000)	(267,583,000)					$ (1,000)
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)							(754,000)
Issuance of Common Stock in connection with conversion of convertible senior notes	691,356,000	691,354,000					$ 2,000
Issuance of Common Stock in connection with conversion of convertible senior notes (in shares)							2,018,000
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	13,125,000	13,125,000
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)							21,000
Issuance of restricted Common Stock under Long-Term Incentive Plan	0
Issuance of restricted Common Stock under Long-Term Incentive Plan (shares)							8,000
Conversion of Class A Stock to Common Stock (shares)						(47,000)	47,000
Stock-based compensation charges	326,815,000	326,815,000
Excess tax benefit from stock-based compensation	439,278,000	439,278,000
Acquisition of Common Stock in connection with exercise of convertible note hedges	0	169,530,000		$ (169,530,000)
Acquisition of Common Stock in connection with exercise of convertible note hedges (in shares)				(2,018,000)
Reduction of warrants	(294,552,000)	(294,552,000)
Reclassification of warrant liability	(148,496,000)	(148,496,000)
Reduction of equity component of convertible senior notes	(691,869,000)	(691,869,000)
Net income	338,126,000		338,126,000
Other comprehensive income (loss), net of tax	53,439,000				53,439,000
Balance at Dec. 31, 2014	2,550,251,000	2,450,782,000	216,644,000	$ (169,530,000)	52,251,000	$ 2,000	$ 102,000
Balance (shares) at Dec. 31, 2014				(2,018,000)		1,973,000	102,475,000
Other Liabilities, Fair Value Disclosure								$ 87,500,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	215,462,000	215,460,000					$ 2,000
Issuance of Common Stock in connection with exercise of stock options (shares)							2,457,000
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(160,538,000)	(160,538,000)					$ 0
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)							(298,000)
Issuance of Common Stock in connection with conversion of convertible senior notes	818,360,000	818,358,000					$ 2,000
Issuance of Common Stock in connection with conversion of convertible senior notes (in shares)							1,625,000
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	15,382,000	15,382,000
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)							31,000
Issuance of restricted Common Stock under Long-Term Incentive Plan	0
Issuance of restricted Common Stock under Long-Term Incentive Plan (shares)							28,000
Conversion of Class A Stock to Common Stock (shares)						(60,000)	60,000
Stock-based compensation charges	464,022,000	464,022,000
Excess tax benefit from stock-based compensation	405,317,000	405,317,000
Acquisition of Common Stock in connection with exercise of convertible note hedges	0	136,539,000		$ (136,539,000)
Acquisition of Common Stock in connection with exercise of convertible note hedges (in shares)				(1,625,088)
Reduction of warrants	(449,456,000)	(449,456,000)
Reclassification of warrant liability	23,317,000	23,317,000
Reduction of equity component of convertible senior notes	(819,657,000)	(819,657,000)
Net income	636,056,000		636,056,000
Other comprehensive income (loss), net of tax	(43,679,000)				(43,679,000)
Balance at Dec. 31, 2015	3,654,837,000	3,099,526,000	852,700,000	$ (306,069,000)	8,572,000	$ 2,000	$ 106,000
Balance (shares) at Dec. 31, 2015				(3,643,000)		1,913,000	106,378,000
Other Liabilities, Fair Value Disclosure								0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock in connection with exercise of stock options	115,182,000	115,180,000					$ 2,000
Issuance of Common Stock in connection with exercise of stock options (shares)							1,697,000
Common Stock tendered upon exercise of stock options in connection with employee tax obligations	(143,182,000)	(143,182,000)					$ 0
Common Stock tendered upon exercise of stock options in connection with employee tax obligations (in shares)							(382,000)
Issuance of Common Stock in connection with conversion of convertible senior notes	48,004,000	48,004,000					$ 0
Issuance of Common Stock in connection with conversion of convertible senior notes (in shares)							121,000
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution	16,561,000	16,561,000
Issuance of Common Stock in connection with Company 401(k) Savings Plan contribution (shares)							27,000
Issuance of restricted Common Stock under Long-Term Incentive Plan	0
Issuance of restricted Common Stock under Long-Term Incentive Plan (shares)							17,000
Conversion of Class A Stock to Common Stock (shares)						(2,000)	2,000
Stock-based compensation charges	574,887,000	574,887,000
Acquisition of Common Stock in connection with exercise of convertible note hedges	0	10,171,000		$ (10,171,000)
Acquisition of Common Stock in connection with exercise of convertible note hedges (in shares)				(121,048)
Reduction of warrants	(643,365,000)	(643,365,000)
Reduction of equity component of convertible senior notes	(47,789,000)	(47,789,000)
Net income	895,522,000		895,522,000
Other comprehensive income (loss), net of tax	(21,412,000)				(21,412,000)
Balance at Dec. 31, 2016	$ 4,449,245,000	$ 3,029,993,000	$ 1,748,222,000	$ (316,240,000)	$ (12,840,000)	$ 2,000	$ 108,000
Balance (shares) at Dec. 31, 2016				(3,764,000)		1,911,000	107,860,000
Other Liabilities, Fair Value Disclosure								$ 0

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 895,522	$ 636,056	$ 338,126
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	104,745	74,909	52,686
Non-cash compensation expense	559,878	459,049	321,750
Other non-cash charges and expenses, net	45,139	52,562	77,571
Deferred Taxes	(360,078)	(121,623)	(53,276)
Changes in assets and liabilites
Increase in Sanofi, Bayer, and trade accounts receivable	(143,827)	(491,421)	(34,927)
Increase in Inventories	(149,776)	(111,825)	(56,947)
Decrease (increase) in prepaid expenses and other assets	23,543	(79,476)	(45,327)
Increase (decrease) in deferred revenue	244,270	608,892	(8,403)
Increase in accounts payable, accrued expenses and other liabilities	253,980	303,657	161,182
Total adjustments	577,874	694,724	414,309
Net cash provided by operating activities	1,473,396	1,330,780	752,435
Cash flows from investing activities:
Purchases of marketable securities	(809,419)	(557,105)	(564,188)
Sales or maturities of marketable securities	274,456	327,437	476,417
Capital expenditures	(511,941)	(677,933)	(333,006)
Net cash used in by investing activities	(1,046,904)	(907,601)	(420,777)
Cash flows from financing activities:
(Payments) proceeds in connection with capital and facility lease obligations	(27,689)	26,020	(1,095)
Repayments of convertible senior notes	(12,894)	(166,467)	(220,639)
Payments in connection with reduction of outstanding warrants	(643,365)	(573,487)	(294,552)
Proceeds from issuance of Common Stock	126,739	206,358	126,045
Payments in connection with Common Stock tendered for employee tax obligations	(143,182)	(160,537)	(267,584)
Excess tax benefit from stock-based compensation	0	405,317	439,278
Net cash (used in) provided by financing activities	(700,391)	(262,796)	(218,547)
Net (decrease) increase in cash and cash equivalents	(273,899)	160,383	113,111
Cash and cash equivalents at beginning of period	809,102	648,719	535,608
Cash and cash equivalents at end of period	535,203	809,102	648,719
Cash paid for interest (net of amounts capitalized)	5,454	10,582	20,348
Cash paid for income taxes	$ 481,360	276,092	59,847
Warrant
Cash flows from financing activities:
Payments in connection with reduction of outstanding warrants		$ (399,500)	$ (294,600)

Business Overview and Summary o

Business Overview and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Business Overview and Summary of Significant Accounting Policies Organization and Business Regeneron Pharmaceuticals, Inc. and its subsidiaries (collectively, the "Company" or "Regeneron") is a fully integrated biopharmaceutical company that discovers, invents, develops, manufactures, and commercializes medicines for the treatment of serious medical conditions. The Company has product candidates in development in areas of high unmet medical need, including oncology, rheumatoid arthritis, asthma, atopic dermatitis, pain, and infectious diseases. The Company is a party to collaboration agreements to develop certain of these product candidates (see Note 3). The Company's products that have received marketing approval consist of the following: • EYLEA ® (aflibercept) Injection , known in the scientific literature as VEGF Trap-Eye, which is available in the United States, European Union ("EU"), Japan, and certain other countries outside the United States for the treatment of neovascular age-related macular degeneration ("wet AMD"), diabetic macular edema ("DME"), macular edema following retinal vein occlusion ("RVO"), which includes macular edema following central retinal vein occlusion ("CRVO") and macular edema following branch retinal vein occlusion ("BRVO"). EYLEA is also available in the EU, Japan, and certain other countries outside the United States for the treatment of myopic choroidal neovascularization (mCNV) and in the United States for the treatment of diabetic retinopathy in patients with DME. The Company is collaborating with Bayer on the development and commercialization of EYLEA outside the United States. • Praluent ® (alirocumab) Injection , which is available in the United States where it is indicated as an adjunct to diet and maximally tolerated statin therapy for the treatment of adults with heterozygous familial hypercholesterolemia or clinical atherosclerotic cardiovascular disease ("ASCVD"), who require additional lowering of low-density lipoprotein ("LDL") cholesterol. Praluent is also available in certain countries in Europe for the treatment of adult patients with primary hypercholesterolemia (heterozygous familial hypercholesterolemia ("HeFH") and non-familial) or mixed dyslipidemia as an adjunct to diet: (a) in combination with a statin, or statin with other lipid-lowering therapies in patients unable to reach their LDL-cholesterol goals with the maximally-tolerated dose of a statin, or (b) alone or in combination with other lipid-lowering therapies for patients who are statin intolerant, or for whom a statin is contraindicated. In July 2016, the Japanese Ministry of Health, Labour and Welfare ("MHLW") granted marketing and manufacturing authorization for Praluent for the treatment of uncontrolled LDL cholesterol, in certain adult patients with hypercholesterolemia at high cardiovascular risk. The effect of Praluent on cardiovascular morbidity and mortality has not been determined. The Company is collaborating with Sanofi on the global development and commercialization of Praluent. See Note 17 for information regarding the patent infringement proceedings relating to Praluent, which may impact Praluent's commercial availability in the United States and other jurisdictions. • ARCALYST ® (rilonacept) Injection for Subcutaneous Use , which is available in the United States for the treatment of Cryopyrin-Associated Periodic Syndromes ("CAPS"), including Familial Cold Auto-inflammatory Syndrome ("FCAS") and Muckle-Wells Syndrome ("MWS"), in adults and children 12 and older. • Kevzara TM (sarilumab) Solution for Subcutaneous Injection . In January 2017, Health Canada approved Kevraza for the treatment of adult patients with moderately to severely active rheumatoid arthritis who have an inadequate response to or intolerance to one or more biologic or non-biologic disease modifying anti-rheumatic drugs ("DMARDs"). This is the first approval of Kevzara worldwide. • ZALTRAP ® (ziv-aflibercept) Injection for Intravenous Infusion , known in the scientific literature as VEGF Trap, which is available in the United States, EU, and certain other countries for treatment, in combination with 5-fluorouracil, leucovorin, irinotecan ("FOLFIRI"), of patients with metastatic colorectal cancer ("mCRC") that is resistant to or has progressed following an oxaliplatin-containing regimen. Pursuant to a 2015 amended and restated ZALTRAP agreement ("Amended ZALTRAP Agreement"), Sanofi is solely responsible for the development and commercialization of ZALTRAP, and Sanofi pays the Company a percentage of aggregate net sales of ZALTRAP. The Company operates in one business segment, which includes all activities related to the discovery, development, and commercialization of pharmaceutical products for the treatment of serious medical conditions. The Company's business is subject to certain risks including, but not limited to, uncertainties relating to conducting pharmaceutical research, product development, obtaining regulatory approvals, market acceptance, competition, and obtaining and enforcing patents. Basis of Presentation The consolidated financial statements include the accounts of Regeneron and its wholly-owned subsidiaries. Intercompany balances and transactions are eliminated in consolidation. Certain reclassifications have been made to prior period amounts to conform with the current period's presentation. Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles 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. Estimates which could have a significant impact on the Company's financial statements include provisions related to product sales, such as rebates, chargebacks, and distribution-related fees; periods over which payments, including non-refundable up-front, license, and milestone payments, are recognized as revenue in connection with collaboration and other agreements; periods over which certain clinical trial costs are recognized; fair value of stock options; inventory that may expire prior to expected sale or has a cost basis in excess of its estimated realizable value; capitalization of inventory costs associated with the Company's products prior to regulatory approval; provisions for loss contingencies; deferred tax asset valuation allowances; and the assessment of uncertain tax positions. With respect to the Company's collaborations with Sanofi and Bayer: • Included in Sanofi collaboration revenue is the Company's share of profits or losses from commercialization of antibodies, which is provided by Sanofi, and includes an estimate of the Company's share of profits or losses for the most recent fiscal quarter. • Included in Bayer collaboration revenue is the Company's share of profits or losses from commercialization of EYLEA outside the United States, which is provided by Bayer, and includes an estimate of the Company's share of profits or losses for the most recent fiscal quarter. • Included in research and development expenses is the Company's share of development expenses incurred by Bayer and Sanofi, including the Company's share of Bayer and Sanofi estimated development expenses for the most recent fiscal quarter. These estimates for the most recent period are adjusted on a prospective basis, if necessary, in the subsequent period to reflect actual amounts. Cash and Cash Equivalents The Company considers all highly liquid debt instruments with a maturity of three months or less when purchased to be cash equivalents. The carrying amount reported in the Consolidated Balance Sheet for cash and cash equivalents approximates its fair value. Marketable Securities The Company has an investment policy that includes guidelines on acceptable investment securities, minimum credit quality, maturity parameters, and concentration and diversification. The Company invests its excess cash primarily in marketable securities issued by investment grade institutions. The Company considers its marketable securities to be "available-for-sale," as defined by authoritative guidance issued by the Financial Accounting Standards Board ("FASB"). These assets are carried at fair value and the unrealized gains and losses are included in accumulated other comprehensive income (loss). Realized gains and losses on marketable securities are included as a component of other income (expense), net. The Company reviews its portfolio of marketable securities, using both quantitative and qualitative factors, to determine if declines in fair value below cost are other-than-temporary. If a decline in the fair value of a marketable security in the Company's investment portfolio is deemed to be other-than-temporary, the Company writes down the cost basis of the security to its current fair value and recognizes a loss as a charge against income. Accounts Receivable - Trade The Company's trade accounts receivable arise from product sales and represent amounts due from its distributors and specialty pharmacies (collectively, the Company's "customers"), which are all located in the United States. The Company monitors the financial performance and credit worthiness of its large customers so that it can properly assess and respond to changes in their credit profile. The Company provides reserves against trade receivables for estimated losses, if any, that may result from a customer's inability to pay. Amounts determined to be uncollectible are written-off against the reserve. Inventories Inventories are stated at the lower of cost or estimated realizable value. The Company determines the cost of inventory using the first-in, first-out, or FIFO, method. The Company capitalizes inventory costs associated with the Company's products prior to regulatory approval when, based on management's judgment, future commercialization is considered probable and the future economic benefit is expected to be realized; otherwise, such costs are expensed as research and development. The determination to capitalize inventory costs is based on various factors, including status and expectations of the regulatory approval process, any known safety or efficacy concerns, potential labeling restrictions, and any other impediments to obtaining regulatory approval. The Company periodically analyzes its inventory levels to identify inventory that may expire prior to expected sale or has a cost basis in excess of its estimated realizable value, and writes-down such inventories as appropriate. In addition, the Company's products are subject to strict quality control and monitoring which the Company performs throughout the manufacturing process. If certain batches or units of product no longer meet quality specifications or become obsolete due to expiration, the Company records a charge to cost of goods sold to write down such unmarketable inventory to its estimated realizable value. Property, Plant, and Equipment Property, plant, and equipment are stated at cost, net of accumulated depreciation. Depreciation is provided on a straight-line basis over the estimated useful lives of the assets. Leasehold improvements are amortized over the shorter of the estimated useful lives of the assets or the lease term. Costs of construction of certain long-lived assets include capitalized interest, which is amortized over the estimated useful life of the related asset. Expenditures for maintenance and repairs which do not materially extend the useful lives of the assets are charged to expense as incurred. The cost and accumulated depreciation or amortization of assets retired or sold are removed from the respective accounts, and any gain or loss is recognized in operations. The estimated useful lives of property, plant, and equipment are as follows: Building and improvements 10-40 years Laboratory and other equipment 3-10 years Furniture and fixtures 5 years The Company periodically assesses the recoverability of long-lived assets, such as property, plant, and equipment, and evaluates such assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Revenue Recognition a. Product Revenue Product revenue consists of U.S. sales of EYLEA and ARCALYST. Revenue from product sales is recognized when persuasive evidence of an arrangement exists, title to product and associated risk of loss have passed to the customer, the price is fixed or determinable, collection from the customer is reasonably assured, the Company has no further performance obligations, and returns can be reasonably estimated. The Company's written contracts with its customers stipulate product is shipped freight on board destination (FOB destination). The Company records revenue from product sales upon delivery to its customers. The Company sells EYLEA in the United States to several distributors and specialty pharmacies. The Company sells ARCALYST in the United States to two specialty pharmacies. Under these distribution models, the distributors and specialty pharmacies generally take physical delivery of product. For EYLEA, the distributors and specialty pharmacies generally sell the product directly to healthcare providers, whereas for ARCALYST, the specialty pharmacies sell the product directly to patients. Revenue from product sales is recorded net of applicable provisions for rebates and chargebacks under governmental and other programs, distribution-related fees, and other sales-related deductions. Calculating these provisions involves estimates and judgments. The Company reviews its estimates of rebates, chargebacks, and other applicable provisions each period and records any necessary adjustments in the current period's net product sales. Government Rebates and Chargebacks: The Company estimates reductions to product sales for Medicaid and Veterans' Administration ("VA") programs, and for certain other qualifying federal and state government programs. Based upon the Company's contracts with government agencies, statutorily-defined discounts applicable to government-funded programs, historical experience, and estimated payer mix, the Company estimates and records an allowance for rebates and chargebacks. The Company's liability for Medicaid rebates consists of estimates for claims that a state will make for a current quarter, claims for prior quarters that have been estimated for which an invoice has not been received, and invoices received for claims from prior quarters that have not been paid. The Company's reserves related to discounted pricing to VA, Public Health Services ("PHS"), and other institutions (collectively "qualified healthcare providers") represent the Company's estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices the Company charges to its customers (i.e., distributors and specialty pharmacies). The Company's customers charge the Company for the difference between what they pay for the products and the ultimate selling price to the qualified healthcare providers. The Company's reserve for this discounted pricing is based on expected sales to qualified healthcare providers and the chargebacks that customers have already claimed. Distribution-Related Fees: The Company has written contracts with its customers that include terms for distribution-related fees. The Company estimates and records distribution and related fees due to its customers based on gross sales. Prompt Pay Discounts: No prompt pay discounts are currently offered to the Company's customers on sales of EYLEA. In connection with sales of ARCALYST, the Company offers discounts to its customers for prompt payments. The Company estimates these discounts based on customer terms and historical experience, and expects that its customers will always take advantage of this discount. Therefore, the Company accrues 100% of the prompt pay discount that is based on the gross amount of each ARCALYST invoice, at the time of sale. Product Returns: Consistent with industry practice, the Company offers its customers a limited right to return product purchased directly from the Company, which is principally based upon the product's expiration date. The Company will accept returns for three months prior to and up to six months after the product expiration date. Product returned is generally not resalable given the nature of the Company's products and method of administration. The Company develops estimates for product returns based upon historical experience, inventory levels in the distribution channel, shelf life of the product, and other relevant factors. The Company monitors product supply levels in the distribution channel, as well as sales by its customers of EYLEA to healthcare providers and ARCALYST to patients using product-specific data provided by its customers. If necessary, the Company's estimates of product returns may be adjusted in the future based on actual returns experience, known or expected changes in the marketplace, or other factors. b. Collaboration Revenue The Company earns collaboration revenue in connection with collaboration agreements to develop and commercialize product candidates and utilize the Company's technology platforms. These arrangements may require the Company to deliver various rights, services, and/or goods across the entire life cycle of a product or product candidate. The terms of these agreements typically include that consideration be provided to the Company in the form of non-refundable up-front payments, milestone payments, payments for development and commercialization activities, and sharing of profits or losses arising from the commercialization of products. In connection with non-refundable up-front payments, the Company's performance period estimates are principally based on projections of the scope, progress, and results of its research and development activities. Due to the variability in the scope of activities and length of time necessary to develop a drug product, changes to development plans as programs progress, and uncertainty in the ultimate requirements to obtain regulatory approval for commercialization, revisions to performance period estimates are likely to occur periodically, and could result in material changes to the amount of revenue recognized each year in the future. In addition, estimated performance periods may change if development programs encounter delays, or the Company and its collaborators decide to expand or contract the clinical plans for a drug candidate in various disease indications. In arrangements involving multiple deliverables, each required deliverable is evaluated to determine whether it qualifies as a separate unit of accounting. This determination is generally based on whether the deliverables in the arrangement meet certain criteria, including whether the delivered item or items has value to the collaborator on a standalone basis. The arrangement's consideration that is fixed and determinable is allocated to each separate unit of accounting based on the relative selling price of each deliverable. If multiple collaboration activities or rights do not require separation, they are combined into a single unit of accounting and recognized over the performance period, which is the period over which the Company is obligated to deliver goods or services. The Company estimates its performance period based on the specific terms of each agreement, and adjusts the performance periods, if appropriate, based on the applicable facts and circumstances. Payments which are based on achieving a specific substantive performance milestone, involving a degree of risk, are recognized as revenue when the milestone is achieved and the related payment is due and non-refundable, provided there is no future service obligation associated with that milestone. Substantive performance milestones typically consist of significant achievements in the development life-cycle of the related product candidate, such as completion of clinical trials, filing for approval with regulatory agencies, and receipt of approvals by regulatory agencies. In determining whether a payment is deemed to be a substantive performance milestone, the Company takes into consideration (i) the enhancement in value to the related development product candidate, (ii) the Company's performance and the relative level of effort required to achieve the milestone, (iii) whether the milestone relates solely to past performance, and (iv) whether the milestone payment is considered reasonable relative to all of the deliverables and payment terms. Payments for achieving milestones which are not considered substantive are deferred and recognized over the related performance period. The Company enters into collaboration agreements that include varying arrangements regarding which parties perform and bear the costs of research and development activities. The Company may share the costs of research and development activities with a collaborator, or the Company may be reimbursed for all or a significant portion of the costs of the Company's research and development activities. The Company records its internal and third-party development costs associated with these collaborations as research and development expenses. When the Company is entitled to reimbursement of all or a portion of the research and development expenses that it incurs under a collaboration, the Company records those reimbursable amounts as collaboration revenue proportionately as the Company recognizes its expenses. If the collaboration is a cost-sharing arrangement in which both the Company and its collaborator perform development work and share costs, the Company also recognizes, as research and development expense in the period when its collaborator incurs development expenses, the portion of the collaborator's development expenses that the Company is obligated to reimburse. The Company may also be obligated to use commercially reasonable efforts to supply commercial bulk product to its collaborators. In such cases, the Company is reimbursed for its manufacturing costs as commercial product is shipped to its collaborators; however, recognition of such cost reimbursements as collaboration revenue is deferred until the product is sold by the Company's collaborators to third-party customers, at which time the Company's risk of inventory loss no longer exists. In addition, at that time, the related manufacturing costs for the sold product, which had been capitalized into inventory, are recognized by the Company. Under the Company's collaboration agreements, product sales and cost of sales for products which are currently approved are recorded by the Company's collaborators. The Company shares in any profits or losses arising from the commercialization of such products. The Company records its share of the profits or losses from commercialization of such products, representing net product sales less cost of goods sold and shared commercialization and other expenses, as collaboration revenue. Research and Development Expenses Research and development expenses include costs directly attributable to the conduct of research and development programs, including the cost of salaries, payroll taxes, employee benefits, materials, supplies, depreciation on and maintenance of research equipment, costs related to research collaboration and licensing agreements, the cost of services provided by outside contractors, including services related to the Company's clinical trials, clinical trial expenses, the full cost of manufacturing drug for use in research, preclinical development, and clinical trials, amounts that the Company is obligated to reimburse to collaborators for research and development expenses that they incur, and the allocable portions of facility costs, such as rent, utilities, insurance, repairs and maintenance, depreciation, and general support services. Costs associated with research and development are expensed. Clinical trial costs are a significant component of research and development expenses and include costs associated with third-party contractors. The Company outsources a substantial portion of its clinical trial activities, utilizing external entities such as contract research organizations ("CROs"), independent clinical investigators, and other third-party service providers to assist the Company with the execution of its clinical studies. For each clinical trial that the Company conducts, certain clinical trial costs are expensed immediately, while others are expensed over time based on the expected total number of patients in the trial, the rate at which patients enter the trial, and/or the period over which clinical investigators or CROs are expected to provide services. Clinical activities which relate principally to clinical sites and other administrative functions to manage the Company's clinical trials are performed primarily by CROs. CROs typically perform most of the start-up activities for the Company's trials, including document preparation, site identification, screening and preparation, pre-study visits, training, and program management. These start-up costs usually occur within a few months after the contract has been executed and are event driven in nature. The remaining activities and related costs, such as patient monitoring and administration, generally occur ratably throughout the life of the individual contract or study. In the event of early termination of a clinical trial, the Company accrues and recognizes expenses in an amount based on its estimate of the remaining non-cancelable obligations associated with the winding down of the clinical trial and/or penalties. For clinical study sites, where payments are made periodically on a per-patient basis to the institutions performing the clinical study, the Company accrues expenses on an estimated cost-per-patient basis, based on subject enrollment and activity in each quarter. The amount of clinical study expense recognized in a quarter may vary from period to period based on the duration and progress of the study, the activities to be performed by the sites each quarter, the required level of patient enrollment, the rate at which patients actually enroll in and drop-out of the clinical study, and the number of sites involved in the study. Clinical trials that bear the greatest risk of change in estimates are typically those that have a significant number of sites, require a large number of patients, have complex patient screening requirements, and span multiple years. During the course of a trial, the Company adjusts its rate of clinical expense recognition if actual results differ from the Company's estimates. The Company's estimates and assumptions for clinical expense recognition could differ significantly from its actual results, which could cause material increases or decreases in research and development expenses in future periods when the actual results become known. Stock-based Compensation The Company recognizes stock-based compensation expense for grants of stock option awards and restricted stock under the Company's Long-Term Incentive Plans to employees and non-employee members of the Company's board of directors based on the grant-date fair value of those awards. The grant-date fair value of an award is generally recognized as compensation expense over the award's requisite service period. The Company uses the Black-Scholes model to compute the estimated fair value of stock option awards. Using this model, fair value is calculated based on assumptions with respect to (i) expected volatility of the Company's Common Stock price, (ii) the periods of time over which employees and members of the board of directors are expected to hold their options prior to exercise (expected lives), (iii) expected dividend yield on the Common Stock, and (iv) risk-free interest rates. Stock-based compensation expense also includes an estimate, which is made at the time of grant, of the number of awards that are expected to be forfeited. This estimate is revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined on the basis of the difference between the tax basis of assets and liabilities and their respective financial reporting amounts ("temporary differences") at enacted tax rates in effect for the years in which the differences are expected to reverse. A valuation allowance is established for deferred tax assets for which it is more likely than not that some portion or all of the deferred tax assets will not be realized. Uncertain tax positions, for which management's assessment is that there is more than a 50% probability of sustaining the position upon challenge by a taxing authority based upon its technical merits, are subjected to certain recognition and measurement criteria. The Company re-evaluates uncertain tax positions and consider various factors, including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, and changes in facts or circumstances related to a tax position. The Company adjusts the level of the liability to reflect any subsequent changes in the relevant facts and circumstances surrounding the uncertain positions. The Company recognizes interest and penalties related to income tax matters in income tax expense. Per Share Data Basic net income per share is computed by dividing net income by the weighted average number of shares of Common Stock and Class A Stock outstanding. Net income per share is presented on a combined basis, inclusive of Common Stock and Class A Stock outstanding, as each class of stock has equivalent economic rights. Basic net income per share excludes restricted stock awards until vested. Diluted net income per share includes the potential dilutive effect of common stock equivalents as if such securities were converted or exercised during the period, when the effect is dilutive. Common stock equivalents include: (i) outstanding stock options and restricted stock awards under the Company's Long-Term Incentive Plans, which are included under the "treasury stock method" when dilutive, (ii) Common Stock to be issued upon the assumed conversion of the Company's convertible senior notes, which are included under the "if-converted method" when dilutive, and (iii) Common Stock to be issued upon the exercise of outstanding warrants, which are included under the "treasury stock method" when dilutive. Concentration of Credit Risk Financial instruments which potentially expose the Company to concentrations of credit risk consist of cash, cash equivalents, certain financial instruments, and accounts receivable. A large portion of the Company's cash is held by a few major financial institutions. In accordance with the Company's policies, the Company mandates asset diversification and monitors exposure with its counterparties. Concentrations of credit risk with respect to accounts receivable are significant. Accounts receivable from product sales of EYLEA and ARCALYST are due from several distributors and specialty pharmacies, who are the Company's customers. As of December 31, 2016 , three individual customers accounted for 99% of the Company's net trade accounts receivable balances. As of December 31, 2015, two individual customers accounted for 94% of the Company's net trade accounts receivable balances.The Company has contractual payment terms with each of its customers, and the Company monitors its customers' financial performance and credit worthiness so that it can properly assess and respond to any changes in their credit profile. In addition, the Company may insure a portion of its accounts receivables within its overall risk management practices. As of December 31, 2016 and 2015, there were no reserves against trade accounts receivable. In addition, during the years ended December 31, 2016, 2015, and 2014, the Company did no t recognize any charges for write-offs of trade accounts receivable. Recently Issued Accounting Standards In May 2014, the FASB issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers , which will replace existing revenue recognition guidance. The new standard requires an entity to recognize the amount of revenue to

Net Product Sales

Net Product Sales	12 Months Ended
	Dec. 31, 2016
Revenues [Abstract]
Net Product Sales	Product Sales Net product sales consist of U.S. sales of EYLEA and ARCALYST. The Company received marketing approval from the FDA for EYLEA for the treatment of wet AMD in 2011, macular edema following CRVO in 2012, DME and macular edema following BRVO in 2014, and diabetic retinopathy in patients with DME in 2015. EYLEA net product sales in the United States totaled $3,323.1 million , $2,676.0 million , and $1,736.4 million for the years ended December 31, 2016 , 2015, and 2014, respectively. ARCALYST net product sales totaled $15.3 million , $13.5 million , and $14.4 million for the years ended December 31, 2016 , 2015, and 2014, respectively. The Company's product sales to certain customers that accounted for more than 10% of total gross product revenue for each of the years ended December 31, 2016, 2015, and 2014. Sales to each of these customers as a percentage of the Company's total gross product revenue are as follows: Year Ended December 31, 2016 2015 2014 Besse Medical, a subsidiary of AmerisourceBergen Corporation 55 % 67 % 73 % McKesson Corporation 28 % 26 % 20 % Curascript SD Specialty Distribution, a subsidiary of Express Scripts 16 % ** ** ** For the periods ending December 31, 2015 and 2014, sales to Curascript SD Specialty Distribution represented less than 10% of total gross product revenue. Revenue from product sales is recorded net of applicable provisions for rebates and chargebacks, distribution-related fees, and other sales-related deductions. The following table summarizes the provisions, and credits/payments, for these sales-related deductions for the years ended December 31, 2016, 2015, and 2014. Rebates & Chargebacks Distribution- Related Fees Other Sales- Related Deductions Total Balance as of December 31, 2013 $ 4,400 $ 19,663 $ 538 $ 24,601 Provision related to current period sales 33,117 77,160 1,578 111,855 Credits/payments (34,434 ) (75,657 ) (1,584 ) (111,675 ) Balance as of December 31, 2014 3,083 21,166 532 24,781 Provision related to current period sales 61,124 122,466 9,600 193,190 Credits/payments (57,788 ) (95,319 ) (9,615 ) (162,722 ) Balance as of December 31, 2015 6,419 48,313 517 55,249 Provision related to current period sales 93,385 154,477 30,442 278,304 Credits/payments (87,092 ) (173,325 ) (27,285 ) (287,702 ) Balance as of December 31, 2016 $ 12,712 $ 29,465 $ 3,674 $ 45,851

Collaboration Agreements

Collaboration Agreements	12 Months Ended
	Dec. 31, 2016
Collaboration Agreement [Abstract]
Collaboration and Contract Research Agreements	Collaboration Agreements The Company has entered into various agreements related to its activities to research, develop, manufacture, and commercialize product candidates and utilize its technology platforms. Significant agreements of this kind are described below. a. Sanofi Sanofi owned a total of 23,418,396 shares of the Company's Common Stock as of December 31, 2016, a portion of which was purchased in connection with the companies' ZALTRAP and antibody collaborations described below. See Note 13 for a description of the investor agreement between Sanofi and the Company. The collaboration revenue the Company earned from Sanofi is detailed below: Year Ended December 31, Sanofi Collaboration Revenue 2016 2015 2014 Antibody: Reimbursement of Regeneron research and development expenses $ 564,900 $ 735,439 $ 547,761 Reimbursement of Regeneron commercialization-related expenses 322,149 157,350 19,480 Regeneron's share of losses in connection with commercialization of antibodies (459,058 ) (240,042 ) (41,378 ) Other 12,177 10,243 10,243 Total Antibody 440,168 662,990 536,106 Immuno-oncology: Reimbursement of Regeneron research and development expenses 138,497 39,961 — Other 80,000 40,000 — Total Immuno-oncology 218,497 79,961 — ZALTRAP: Regeneron's share of losses in connection with commercialization of ZALTRAP — — (4,715 ) Reimbursement of Regeneron research and development expenses — 686 4,806 Other — 15,236 5,102 Total ZALTRAP — 15,922 5,193 $ 658,665 $ 758,873 $ 541,299 Other selected financial information in connection with the Company's collaboration agreements with Sanofi is as follows: As of December 31, 2016 2015 Antibody: Accounts receivable, net $ 47,268 $ 126,687 Deferred revenue 98,741 84,237 Immuno-oncology: Accounts receivable, net $ 40,647 $ 21,394 Deferred revenue 520,000 600,000 Antibodies In November 2007, the Company entered into a global, strategic collaboration with Sanofi to discover, develop, and commercialize fully human monoclonal antibodies (the "Antibody Collaboration") . The Antibody Collaboration is governed by the companies' Discovery and Preclinical Development Agreement ("Antibody Discovery Agreement") and a License and Collaboration Agreement (each as amended). In connection with the execution of the Antibody Discovery Agreement in 2007, the Company received a non-refundable up-front payment of $85.0 million from Sanofi. In addition, under the Antibody Discovery Agreement, Sanofi is funding the Company's research to identify and validate potential drug discovery targets and develop fully human monoclonal antibodies against these targets. In November 2009, the Company and Sanofi amended these collaboration agreements to expand and extend the Antibody Collaboration. Pursuant to the Antibody Discovery Agreement, as amended, Sanofi agreed to fund up to $160.0 million per year of the Company's research activities in 2010 through 2017. However, in July 2015, in connection with the Company’s new immuno-oncology collaboration with Sanofi, as described below, the Company’s Antibody Discovery Agreement and License and Collaboration Agreement with Sanofi were each amended. In connection with these amendments, Sanofi's funding of the Company’s antibody discovery activities under the existing Antibody Collaboration was reduced to up to $145.0 million in 2015, and up to $130.0 million in both 2016 and 2017, or an aggregate reduction of $75.0 million over this three -year period. In addition, the Company's discovery activities to identify and validate potential drug discovery targets in the field of immuno-oncology and develop fully human monoclonal antibodies against these targets will be funded by Sanofi under the terms of the companies’ new immuno-oncology collaboration. Sanofi has the right to extend antibody development and preclinical activities relating to selected programs for up to an additional three years after 2017. Sanofi must identify any programs to be extended by June 30, 2017, and the Company and Sanofi must then agree on a plan and budget for the extended activities. During the extended period, the Company will use commercially reasonable efforts to develop such antibodies and conduct preclinical activities through IND preparation. After 2017, funding from Sanofi under the Antibody Discovery Agreement will cease to continue, except with regard to the programs for which Sanofi has exercised its extension right. For each drug candidate identified under the Antibody Discovery Agreement (including drug candidates developed during the extended period of up to an additional three years described above), Sanofi has the option to license rights to the candidate under the License and Collaboration Agreement. If it elects to do so, Sanofi will co-develop the drug candidate with the Company through product approval. Under certain defined circumstances, upon exercising its option to license rights to particular candidates, Sanofi must make a $10.0 million substantive milestone payment to the Company. If Sanofi does not exercise its option to license rights to a particular drug candidate under the License and Collaboration Agreement, or if Sanofi elects not to continue to co-develop a product candidate, the Company retains the exclusive right to develop and commercialize such drug candidate and Sanofi will receive a royalty on sales, if any. Under the License and Collaboration Agreement, agreed-upon worldwide development expenses incurred by both companies during the term of the agreement are funded by Sanofi, except that following receipt of the first positive Phase 3 trial results for a co-developed drug candidate, subsequent Phase 3 trial-related costs for that drug candidate ("Shared Phase 3 Trial Costs") are shared 80% by Sanofi and 20% by Regeneron. Consequently, the Company recognized as research and development expense $108.6 million , $92.6 million , and $109.7 million in 2016, 2015, and 2014, respectively, of antibody development expenses that the Company was obligated to reimburse to Sanofi related to Praluent, sarilumab, and, commencing in the first quarter of 2016, dupilumab. If the Antibody Collaboration becomes profitable, Regeneron will be obligated to reimburse Sanofi for 50% of worldwide development expenses that were fully funded by Sanofi and 30% of Shared Phase 3 Trial Costs, in accordance with a defined formula based on the amounts of these expenses and the Company's share of collaboration profits from commercialization of collaboration products. However, the Company is not required to apply more than 10% of its share of the profits from the Antibody Collaboration in any calendar quarter to reimburse Sanofi for these development costs. The Company's contingent reimbursement obligation to Sanofi under the Antibody Collaboration was approximately $2,245 million as of December 31, 2016. Sanofi will lead commercialization activities for products developed under the License and Collaboration Agreement, subject to the Company's right to co-promote such products. The parties equally share profits and losses from sales within the United States. The parties share profits outside the United States on a sliding scale based on sales starting at 65% (Sanofi)/ 35% (Regeneron) and ending at 55% (Sanofi)/ 45% (Regeneron), and losses outside the United States at 55% (Sanofi)/ 45% (Regeneron). In addition to profit sharing, the Company is entitled to receive up to $250.0 million in sales milestone payments, with milestone payments commencing only if and after aggregate annual sales outside the United States exceed $1.0 billion on a rolling twelve -month basis. Regeneron is obligated to use commercially reasonable efforts to supply clinical requirements of each drug candidate under the Antibody Collaboration until commercial supplies of that drug candidate are being manufactured. In connection with the November 2009 amendment of the collaboration's Antibody Discovery Agreement, Sanofi funded $30.0 million of agreed-upon costs the Company incurred to expand its manufacturing capacity at its Rensselaer, New York facilities. Additionally, during 2014, Sanofi agreed to fund up to $17.5 million of agreed-upon costs incurred by the Company in connection with expanding the Company's manufacturing capacity at its Rensselaer, New York facility. Payments received from Sanofi to fund agreed-upon expansions of the Company's manufacturing capacity are initially recorded as deferred revenue by the Company and are being recognized as collaboration revenue over the related performance period. With respect to each antibody product which enters development under the License and Collaboration Agreement, Sanofi or the Company may, by giving twelve months' notice, opt-out of further development and/or commercialization of the product, in which event the other party retains exclusive rights to continue the development and/or commercialization of the product. The Company may also opt-out of the further development of an antibody product if it gives notice to Sanofi within thirty days of the date that Sanofi enters joint development of such antibody product under the License and Collaboration Agreement. Each of the Antibody Discovery Agreement and the License and Collaboration Agreement contains other termination provisions, including for material breach by the other party. Prior to December 31, 2017, Sanofi has the right to terminate the amended Antibody Discovery Agreement without cause with at least three months advance written notice; however, except under defined circumstances, Sanofi would be obligated to immediately pay to the Company the full amount of unpaid research funding during the remaining term of the research agreement through December 31, 2017. Upon termination of the collaboration in its entirety, the Company's obligation to reimburse Sanofi for development costs out of any future profits from collaboration products will terminate. In the event of termination of the amended Antibody Discovery Agreement, the Company retains exclusive rights to continue the development and/or commercialization of such product(s). Upon expiration of the amended Antibody Discovery Agreement, Sanofi has an option to license the Company's VelocImmune ® technology for an annual license fee plus royalties on any future sales of products developed using VelocImmune technology. In connection with the Antibody Collaboration, in August 2008, the Company entered into a separate agreement with Sanofi, which extended through December 2012, to use Regeneron's proprietary VelociGene ® technology platform to supply Sanofi with genetically modified mammalian models of gene function and disease (the " VelociGene Agreement") . The VelociGene Agreement provided for minimum annual order quantities for the term of the agreement, for which the Company received payments totaling $21.5 million . Payments received were initially recorded as deferred revenue by the Company and are being recognized as collaboration revenue over the related performance period. In May 2013, the Company acquired from Sanofi full exclusive rights to two families of novel antibodies invented at Regeneron and previously included in the Company's Antibody Collaboration with Sanofi. The Company acquired full rights to antibodies targeting the platelet derived growth factor (PDGF) family of receptors and ligands in ophthalmology and all other indications and to antibodies targeting the angiopoietin-2 (Ang2) receptor and ligand in ophthalmology. With respect to PDGF antibodies, the Company made two $5.0 million development milestone payments to Sanofi in 2014 and a $10.0 million development milestone payment to Sanofi in 2015, each of which was recorded as research and development expense. In July 2014, in connection with the Company's Antibody Collaboration with Sanofi, the Company purchased an FDA priority review voucher from a third party for $67.5 million . The Company and Sanofi equally shared the priority review voucher's purchase price, and the Company's share of the cost, or $33.8 million , was recorded as a research and development expense during 2014. The Company subsequently transferred the voucher to Sanofi, which used the priority review voucher in connection with the Biologics License Application submission to the FDA for Praluent. "Reimbursement of Regeneron commercialization-related expenses" in the table above represents reimbursement of internal and external costs in connection with preparing to commercialize or commercializing, as applicable, Praluent, sarilumab, and effective in the first quarter of 2016, dupilumab. In 2014, the Company and Sanofi began sharing commercialization expenses related to Praluent and sarilumab in accordance with the companies’ License and Collaboration Agreement. In addition, effective in the first quarter of 2016, the Company and Sanofi also began sharing pre-launch commercialization expenses related to dupilumab. As such, during the same periods that the Company recorded reimbursements from Sanofi related to the Company's commercialization expenses, the Company also recorded its share of losses in connection with the companies preparing to commercialize or commercializing, as applicable, Praluent, sarilumab, and dupilumab within Sanofi collaboration revenue. Immuno-Oncology In July 2015, the Company and Sanofi entered into a collaboration to discover, develop, and commercialize antibody-based cancer treatments in the field of immuno-oncology (the "IO Collaboration"). The IO Collaboration is governed by an Immuno-oncology Discovery and Development Agreement ("IO Discovery Agreement"), and an Immuno-oncology License and Collaboration Agreement ("IO License and Collaboration Agreement"). In connection with the IO Discovery Agreement, Sanofi made a $265.0 million non-refundable up-front payment to the Company. Pursuant to the IO Discovery Agreement, the Company will spend up to $1,090.0 million ("IO Discovery Budget") to identify and validate potential immuno-oncology targets and develop therapeutic antibodies against such targets through clinical proof-of-concept. Sanofi will reimburse the Company for up to $825.0 million ("IO Discovery Funding") of these costs, subject to certain annual limits (including a limit of $150.0 million in 2016), which consists of (i) $750.0 million in new funding and (ii) $75.0 million of funding that would have otherwise been available to Regeneron under the existing Antibody Discovery Agreement, as described above. The term of the IO Discovery Agreement will continue through the later of five years from the effective date of the IO Collaboration or the date the IO Discovery Budget is exhausted, subject to Sanofi’s option to extend it for up to an additional three years for the continued development (and funding) of selected ongoing programs. Pursuant to the IO Discovery Agreement, the Company will be primarily responsible for the design and conduct of all research activities, including target identification and validation, antibody development, preclinical activities, toxicology studies, manufacture of preclinical and clinical supplies, filing of Investigational New Drug ("IND") Applications, and clinical development through proof-of-concept. The Company will reimburse Sanofi for half of the development costs they funded that are attributable to clinical development of antibody product candidates under the IO Discovery Agreement from Regeneron's share of future profits, if any, from commercialized IO Collaboration products to the extent they are sufficient for this purpose. However, the Company is not required to apply more than 10% of its share of the profits from IO Collaboration products in any calendar quarter towards reimbursing Sanofi for these development costs. The Company's contingent reimbursement obligation to Sanofi under the IO Collaboration was approximately $3 million as of December 31, 2016. With regard to product candidates for which proof-of-concept is established, Sanofi will have the option to license rights to the product candidate pursuant to the IO License and Collaboration Agreement (as further described below). If Sanofi does not exercise its option to license rights to a product candidate, the Company will retain the exclusive right to develop and commercialize such product candidate and Sanofi will be entitled to receive a royalty on sales. In connection with the IO License and Collaboration Agreement, Sanofi made a $375.0 million non-refundable up-front payment to the Company. If Sanofi exercises its option to license rights to a product candidate thereunder, it will co-develop the drug candidate with the Company through product approval. Principal control of development of each product candidate that enters development under the IO License and Collaboration Agreement will alternate between the Company and Sanofi on a candidate-by-candidate basis. Sanofi will fund drug candidate development costs up front for the candidates for which it is the principal controlling party and the Company will reimburse half of the total development costs for all such candidates from its share of future IO Collaboration profits to the extent they are sufficient for this purpose, subject to the same 10% reimbursement limitation described above. In addition, Sanofi and the Company will share equally, on an ongoing basis, the development costs for the drug candidates for which the Company is the principal controlling party. The party having principal control over the development of a product candidate will also lead the commercialization activities for such product candidate in the United States. For all products commercialized under the IO License and Collaboration Agreement, Sanofi will lead commercialization activities outside of the United States. Each party will have the right to co-promote licensed products in countries where it is not the lead commercialization party. The parties will share equally in profits and losses in connection with the commercialization of collaboration products. The Company is obligated to use commercially reasonable efforts to supply clinical requirements of each drug candidate under the IO License and Collaboration Agreement until commercial supplies of that IO drug candidate are being manufactured. Under the terms of the IO License and Collaboration Agreement, the parties will also co-develop the Company’s antibody product candidate targeting the receptor known as Programmed Cell Death protein 1, or PD-1 ("REGN2810"). The parties will share equally, on an ongoing basis, development expenses for REGN2810 up to a total of $650.0 million . The Company will have principal control over the development of REGN2810 and will lead commercialization activities in the United States, subject to Sanofi’s right to co-promote, while Sanofi will lead commercialization activities outside of the United States and the parties will equally share profits from worldwide sales. The Company will be entitled to a milestone payment of $375.0 million in the event that sales of all licensed products targeting PD-1 (including REGN2810), together with sales of any other products licensed under the IO License and Collaboration Agreement and sold for use in combination with a licensed product targeting PD-1, equal or exceed $2.0 billion in any consecutive twelve -month period. With respect to each product candidate that enters development under the IO License and Collaboration Agreement, Sanofi or the Company may, by giving twelve months’ notice, opt-out of further development and/or commercialization of the product, in which event the other party will retain exclusive rights to continue the development and/or commercialization of such product. At the inception of the IO Collaboration, the Company's significant deliverables consisted of (i) license to certain rights and intellectual property, (ii) providing research and development services, and (iii) manufacturing clinical supplies. The Company concluded that the license did not have standalone value, primarily due to the fact that such rights were not sold separately by the Company, nor could Sanofi receive any benefit from the license without the fulfillment of other ongoing obligations by the Company, including the clinical supply arrangement. Therefore, the deliverables were considered a single unit of accounting. Consequently, the $640.0 million in aggregate up-front payments was initially recorded as deferred revenue, and is being recognized ratably as revenue over the related performance period. ZALTRAP In September 2003, the Company entered into a collaboration agreement ("ZALTRAP Collaboration Agreement") with Aventis Pharmaceuticals Inc. (predecessor to Sanofi U.S.) to jointly develop and commercialize ZALTRAP. Under the terms of the ZALTRAP Collaboration Agreement, as amended, Regeneron and Sanofi shared co-promotion rights and profits and losses on sales of ZALTRAP outside of Japan, and the Company was entitled to receive a percentage of sales of ZALTRAP in Japan. Sanofi commenced sales of ZALTRAP for patients with mCRC that is resistant to or has progressed following an oxaliplatin-containing regimen, in the United States in 2012 and in certain European and other countries in 2013. In February 2015, the Company and Sanofi entered into the Amended ZALTRAP Agreement. Under the terms of the Amended ZALTRAP Agreement, Sanofi is solely responsible for the development and commercialization of ZALTRAP for cancer indications worldwide. Sanofi bears the cost of all development and commercialization activities and reimburses Regeneron for its costs for any such activities. Sanofi pays the Company a percentage of aggregate net sales of ZALTRAP during each calendar year, which percentage shall be from 15% to 30% , depending on the aggregate net sales of ZALTRAP in such calendar year. The Company will also be paid for all quantities of ZALTRAP manufactured by it, pursuant to a supply agreement, through the earlier of 2021 or the date Sanofi receives regulatory approval to manufacture ZALTRAP at one of its facilities, or a facility of a third party. Unless terminated earlier in accordance with its provisions, the Amended ZALTRAP Agreement will continue to be in effect until such time as neither Sanofi nor its affiliates or sublicensees is developing or commercializing ZALTRAP. As a result of entering into the Amended ZALTRAP Agreement, in the first quarter of 2015, the Company recognized $14.9 million of collaboration revenue, which was previously recorded as deferred revenue under the ZALTRAP Collaboration Agreement, related to (i) amounts that were previously reimbursed by Sanofi for manufacturing commercial supplies of ZALTRAP since the risk of inventory loss no longer existed, and (ii) the unamortized portion of up-front payments from Sanofi as the Company had no further performance obligations. In addition, during the years ended December 31, 2016 and 2015, the Company recorded $26.2 million and $38.8 million , respectively, in other revenue, primarily related to a percentage of net sales of ZALTRAP and manufacturing ZALTRAP commercial supplies for Sanofi. b. Bayer The collaboration revenue the Company earned from Bayer is detailed below: Year Ended December 31, Bayer Collaboration Revenue 2016 2015 2014 EYLEA: Regeneron's net profit in connection with commercialization of EYLEA outside the United States $ 649,232 $ 466,667 $ 301,302 Sales milestones — 15,000 105,000 Cost-sharing of Regeneron EYLEA development expenses 9,010 8,887 23,383 Other 52,527 69,466 52,390 Total EYLEA 710,769 560,020 482,075 PDGFR-beta antibody: Cost-sharing of rinucumab/aflibercept (REGN2176-3) development expenses 10,291 10,075 2,848 Other 9,576 10,393 10,632 Total PDGFR-beta antibody 19,867 20,468 13,480 Ang2 antibody: Cost-sharing of nesvacumab/aflibercept (REGN910-3) development expenses 8,036 — — Other 5,598 — — Total Ang2 antibody 13,634 — — $ 744,270 $ 580,488 $ 495,555 Deferred revenue in connection with the Company's collaboration agreements with Bayer is as follows: As of December 31, 2016 2015 EYLEA $ 62,373 $ 46,694 PDGFR-beta antibody — 9,522 Ang2 antibody 45,739 — EYLEA outside the United States In October 2006, the Company entered into a license and collaboration agreement with Bayer for the global development and commercialization outside the United States of EYLEA. Under the terms of the agreement, Bayer made a non-refundable up-front payment to the Company of $75.0 million . The Company also received from Bayer a $20.0 million development milestone payment in 2007 (which, for the purpose of revenue recognition, was not considered substantive). The $75.0 million up-front payment and the $20.0 million milestone payment are being recognized as collaboration revenue over the related estimated performance period. Since 2009, all agreed-upon EYLEA development expenses incurred by the Company and Bayer, under a global development plan, are being shared equally. The Company is also obligated to use commercially reasonable efforts to supply clinical and commercial bulk product of EYLEA. Bayer has the right to terminate the license and collaboration agreement without cause with at least six months' or twelve months' advance notice depending on defined circumstances at the time of termination. In the event of termination of the agreement for any reason, the Company retains all rights to EYLEA. Bayer commenced sales of EYLEA outside the United States for the treatment of wet AMD in 2012, macular edema secondary to CRVO in 2013, visual impairment due to DME and mCNV (in Japan) in 2014, and macular edema following BRVO in 2015. Bayer markets EYLEA outside the United States, where, for countries other than Japan, the companies share equally in profits and losses from sales of EYLEA. In Japan, the Company is entitled to receive a tiered percentage of between 33.5% and 40.0% of EYLEA net sales. Within the United States, the Company is responsible for commercialization of EYLEA and retains exclusive rights to all profits from such commercialization in the United States. The Company is obligated to reimburse Bayer out of its share of the collaboration profits (including the Company's percentage of sales of EYLEA in Japan) for 50% of the agreed-upon development expenses that Bayer has incurred in accordance with a formula based on the amount of development expenses that Bayer has incurred and the Company's share of the collaboration profits, or at a faster rate at the Company's option. The Company's contingent reimbursement obligation to Bayer was approximately $256 million as of December 31, 2016. In 2014, the Company earned, and recorded as revenue, $90.0 million of sales milestone payments from Bayer upon total aggregate net sales of EYLEA outside the United States achieving certain specified levels starting at $500.0 million over a twelve -month period. In addition, in connection with a November 2013 agreement under which Bayer obtained rights to use certain of the Company's EYLEA clinical data for a regulatory filing, the Company earned, and recorded as revenue, a $15.0 million sales milestone payment in 2014 from Bayer upon total aggregate net sales of specific commercial supplies of EYLEA outside the United States exceeding $100.0 million over a twelve -month period. In 2015, the Company earned, and recorded as revenue, the final sales milestone payment from Bayer, in the amount of $15.0 million , upon total aggregate net sales of specific commercial supplies of EYLEA outside the United States exceeding $200.0 million over a twelve -month period. In January 2014, Bayer decided to participate in the global development and commercialization of EYLEA outside the United States for the treatment of macular edema following BRVO. In connection with this decision, Bayer reimbursed Regeneron $15.7 million for a defined share of the EYLEA global development costs that the Company had incurred prior to February 2014 for the BRVO indication, which was recognized as Bayer collaboration revenue in the first quarter of 2014 and is included with "Cost-sharing of Regeneron EYLEA development expenses" in the table above. In addition, all future agreed upon global EYLEA development expenses incurred in connection with BRVO are being shared equally, and any profits or losses on sales of EYLEA outside of the United States for the treatment of macular edema following BRVO are also shared (for countries other than Japan). The Company is entitled to receive a tiered percentage of EYLEA net sales in Japan. In periods when Bayer incurs agreed-upon EYLEA development expenses that benefit the collaboration and Regeneron, the Company recognizes, as additional research and development expense, the portion of Bayer's EYLEA development expenses that the Company is obligated to reimburse. In 2016, 2015, and 2014, the Company recognized as research and development expense $1.4 million , $13.7 million , and $18.6 million , respectively, of EYLEA development expenses that the Company was obligated to reimburse to Bayer. PDGFR-beta antibody outside the United States In January 2014, the Company entered into a license and collaboration agreement with Bayer governing the joint development and commercialization outside the United States of an antibody product candidate to Platelet Derived Growth Factor Receptor Beta (PDGFR-beta), including REGN2176-3, a combination product candidate comprised of an antibody to PDGFR-beta co-formulated with aflibercept. The agreement provides that the Company would conduct the initial development of the PDGFR-beta antibody through completion of the first proof-of-concept study, upon which Bayer would have a right to opt-in to license and collaborate on further development and commercialization outside the United States. Effective in the first quarter of 2017, the Company has discontinued clinical development of REGN2176-3. In connection with the agreement, Bayer made a $25.5 million non-refundable up-front payment to the Company in January 2014, and is obligated to pay 25% of global development costs and 50% of development costs exclusively for the territory outside the United States under the initial development plan. In addition, Bayer is obligated to reimburse the Company for 50% of development milestone payments to Sanofi related to the Company's acquisition of rights to antibodies targeting the PDGF family of receptors in May 2013. In that regard, Bayer made two $2.5 million development milestone payments to the Company in 2014 (both of which, for the purpose of revenue recognition, were not considered substantive) and a $5.0 million development milestone payment to the Company in 2015 (which was recognized as a substantive milestone). From inception of the agreement until Bayer has the right to opt-in to the collaboration, the Company's sole significant deliverable is research and development services provided in accordance with the agreement. Therefore, the $25.5 million up-front payment was allocated to this deliverable, initially recorded as deferred revenue, and will be recognized as revenue over the related performance period. In addition, the two $2.5 million non-substantive development milestone payments from Bayer were also initially recorded as deferred revenue and will be recognized over the same performance period as the up-front payment. Ang2 antibody outside the United States In March 2016, the Company entered into an agreement with Bayer governing the joint development and commercialization outside the United States of an antibody product candidate to angiopoietin-2 (Ang2), including in combination with aflibercept, for the treatment of ocular diseases or disorders. In connection with the agreement, Bayer made a $50.0 million non-refundable up-front payment to the Company and is obligated to pay 25% of global development costs and 50% of development costs exclusively for the territory outside the United States. The Company is also entitled to receive up to an aggregate of $80.0 million in development milestone payments from Bayer. Bayer will share profits and losses from sales outside the United States equally with the Company, and is responsible for certain royalties payable to Sanofi on sales of the product outside of the United States. Within the United States, the Company has exclusive commercialization rights and will retain all of the profits from sales. At the inception of the agreement, the Company's significant deliverables consisted of (i) a license to certain rights and intellectual property, (ii) providing research and development services, and (iii) manufacturing clinical supplies. The Company concluded that the license did not have standa

Technology Licensing Agreements

Technology Licensing Agreements	12 Months Ended
	Dec. 31, 2016
Technology Licensing Agreements [Abstract]
Technology Licensing Agreements	Technology Licensing Agreement In March 2007, the Company entered into a six -year, non-exclusive license agreement with Astellas Pharma Inc. to allow Astellas to utilize the Company's VelocImmune technology in its internal research programs to discover human monoclonal antibodies. In July 2010, the license agreement with Astellas was amended and extended through June 2023. Under the terms of the amended agreement, Astellas made a $165.0 million up-front payment to the Company in 2010, which was deferred upon receipt and is being recognized as revenue ratably over a seven -year period beginning in mid-2011. In addition, Astellas will make a $130.0 million second payment to the Company in June 2018 unless the license agreement has been terminated prior to that date. Astellas has the right to terminate the agreement at any time by providing 90 days' advance written notice. Under certain limited circumstances, such as a material breach of the agreement by the Company, Astellas may terminate the agreement and receive a refund of a portion of its up-front payment or, if such termination occurs after June 2018, a portion of its second payment, to the Company under the July 2010 amendment to the agreement. The Company is entitled to receive a mid-single digit royalty on any future sales of antibody products discovered by Astellas using the Company's VelocImmune technology. In connection with the Astellas license agreement, for each of the years ended December 31, 2016, 2015, and 2014, the Company recognized $23.6 million of other revenue. In addition, deferred revenue at December 31, 2016 and 2015 in connection with the Astellas license agreement was $33.9 million and $57.4 million , respectively.

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities Marketable securities as of December 31, 2016 and 2015 consist of both debt securities of investment grade issuers as well as equity securities. The following tables summarize the Company's investments in marketable securities: Amortized Unrealized Fair As of December 31, 2016 Cost Basis Gains Losses Value Corporate bonds $ 1,076,964 $ 630 $ (4,743 ) $ 1,072,851 U.S. government and government agency obligations 132,923 58 (641 ) 132,340 Municipal bonds 7,663 1 (20 ) 7,644 Commercial paper 63,074 1 — 63,075 Certificates of deposit 42,612 — — 42,612 Equity securities 57,251 5,551 (13,583 ) 49,219 $ 1,380,487 $ 6,241 $ (18,987 ) $ 1,367,741 As of December 31, 2015 Corporate bonds $ 770,092 $ 156 $ (2,565 ) $ 767,683 U.S. government and government agency obligations 51,402 — (193 ) 51,209 Municipal bonds 17,930 5 (11 ) 17,924 Equity securities 17,005 14,462 — 31,467 $ 856,429 $ 14,623 $ (2,769 ) $ 868,283 The Company classifies its debt security investments based on their contractual maturity dates. The debt securities listed as of December 31, 2016 mature at various dates through November 2021. The fair values of debt security investments by contractual maturity consist of the following: As of December 31, 2016 2015 Maturities within one year $ 503,482 $ 236,121 Maturities after one year through five years 815,040 600,695 $ 1,318,522 $ 836,816 The following table shows the fair value of the Company's marketable securities that have unrealized losses and that are deemed to be only temporarily impaired, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position. Less than 12 Months 12 Months or Greater Total As of December 31, 2016 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Corporate bonds $ 759,222 $ (4,685 ) $ 36,407 $ (58 ) $ 795,629 $ (4,743 ) U.S. government and government agency obligations 81,170 (641 ) — — 81,170 (641 ) Municipal bonds 7,141 (20 ) — — 7,141 (20 ) Equity securities 36,417 (13,583 ) — — 36,417 (13,583 ) $ 883,950 $ (18,929 ) $ 36,407 $ (58 ) $ 920,357 $ (18,987 ) As of December 31, 2015 Corporate bonds $ 668,199 $ (2,473 ) $ 23,749 $ (92 ) $ 691,948 $ (2,565 ) U.S. government and government agency obligations 51,215 (193 ) — — 51,215 (193 ) Municipal bonds 11,917 (11 ) — — 11,917 (11 ) $ 731,331 $ (2,677 ) $ 23,749 $ (92 ) $ 755,080 $ (2,769 ) During the year ended December 31, 2016, the Company recorded an other-than-temporary impairment charge of $9.8 million related to its investment in an equity security. There were no other-than-temporary impairment charges recorded on the Company's investments during 2015 or 2014. Realized gains and losses on sales of marketable securities were not material for the years ended December 31, 2016 and 2015. For the year ended December 31, 2014, total realized gains on sales of marketable securities were not material and there were no realized losses. Changes in the Company's accumulated other comprehensive income (loss) for the years ended December 31, 2016, 2015, and 2014 related to unrealized gains and losses on available-for-sale marketable securities. For the years ended December 31, 2016, 2015, and 2014, amounts reclassified from accumulated other comprehensive income (loss) into other income (expense), net in the Company's Consolidated Statements of Operations were related to the 2016 impairment charge on the equity security and realized gains and losses on sales of marketable securities described above.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company's assets that are measured at fair value on a recurring basis consist of the following: Fair Value Measurements at Reporting Date Using As of December 31, 2016 Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Available-for-sale marketable securities: Corporate bonds $ 1,072,851 — $ 1,072,851 U.S. government and government agency obligations 132,340 — 132,340 Municipal bonds 7,644 — 7,644 Commercial paper 63,075 — 63,075 Certificates of deposit 42,612 — 42,612 Equity securities 49,219 $ 49,219 — $ 1,367,741 $ 49,219 $ 1,318,522 As of December 31, 2015 Available-for-sale marketable securities: Corporate bonds $ 767,683 — $ 767,683 U.S. government and government agency obligations 51,209 — 51,209 Municipal bonds 17,924 — 17,924 Equity securities 31,467 $ 31,467 — $ 868,283 $ 31,467 $ 836,816 Marketable securities included in Level 2 are valued using quoted market prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, or model-based valuations in which significant inputs used are observable. The Company considers market liquidity in determining the fair value for these securities. The Company did no t record any charges for other-than-temporary impairment of its Level 2 marketable securities in 2016 , 2015 , and 2014 . There were no purchases, sales, or maturities of Level 3 marketable securities and no unrealized gains or losses related to Level 3 marketable securities for the years ended December 31, 2016 and 2015. During 2016, transfers of marketable securities from Level 2 to Level 1 were $44.1 million in connection with the lapse of transfer restrictions in November 2016 on the Company's investment in Intellia common shares. During 2015, transfers of marketable securities from Level 2 to Level 1 were $91.4 million in connection with the lapse of the transfer restrictions in January 2015 on the Company's investment in Adverum Biotechnologies, Inc. (formerly Avalanche Biotechnologies, Inc.) common shares. The Company's policy for recognition of transfers between levels of the fair value hierarchy is to recognize any transfer at the beginning of the fiscal quarter in which the determination to transfer was made. There were no other transfers of marketable securities between Levels 1, 2, or 3 classifications during the years ended December 31, 2016 and 2015. As of December 31, 2015 , the Company had $11.2 million in aggregate principal amount of 1.875% convertible senior notes outstanding that matured in October 2016 (see Note 11). The fair value of the outstanding convertible senior notes was estimated to be $72.8 million as of December 31, 2015 , and was determined based on Level 2 inputs, such as market and observable sources.

Inventory

Inventory	12 Months Ended
	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventory	Inventories Inventories consist of the following: As of December 31, 2016 2015 Raw materials $ 92,287 $ 59,151 Work-in-process 202,301 132,068 Finished goods 13,334 11,197 Deferred costs 91,434 36,162 $ 399,356 $ 238,578 Deferred costs represent the costs of product manufactured and shipped to the Company's collaborators for which recognition of revenue has been deferred (see Note 1). For the years ended December 31, 2016 , 2015 , and 2014 , cost of goods sold included inventory write-downs and reserves totaling $14.0 million , $10.6 million , and $6.0 million , respectively.

Property, Plant, and Equipment

Property, Plant, and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant, and Equipment Property, plant, and equipment consist of the following: As of December 31, 2016 2015 Land $ 103,906 $ 77,826 Building and improvements 1,278,283 760,517 Leasehold improvements 101,101 95,226 Construction-in-progress 318,929 579,834 Laboratory and other equipment 554,181 330,432 Furniture, computer and office equipment, and other 152,525 81,381 2,508,925 1,925,216 Less, accumulated depreciation and amortization (425,504 ) (331,096 ) $ 2,083,421 $ 1,594,120 As of December 31, 2016 and 2015, $1,441.2 million and $1,118.4 million , respectively, of the Company's property, plant, and equipment was located in the United States and $642.2 million and $475.7 million , respectively, was located in Ireland. In 2015, the Company acquired an approximate 100-acre parcel of undeveloped land adjacent to the Company's current Tarrytown, New York location for an aggregate purchase price of $73.0 million . Depreciation and amortization expense on property, plant, and equipment amounted to $104.7 million , $74.9 million , and $52.7 million for the years ended December 31, 2016 , 2015 , and 2014 , respectively. Property, plant, and equipment, at cost, as of December 31, 2016 and 2015 included $269.0 million and $254.6 million , respectively, of costs incurred by the Company's landlord to construct laboratory and office facilities in Tarrytown, New York. Additionally, property, plant, and equipment, at cost, as of December 31, 2016 included $138.1 million of leased property under a capital lease. See Note 12a.

Accounts Payable and Accrued Ex

Accounts Payable and Accrued Expenses	12 Months Ended
	Dec. 31, 2016
Payables and Accruals [Abstract]
Accounts Payable and Accrued Expenses	Accounts Payable and Accrued Expenses Accounts payable and accrued expenses consist of the following: As of December 31, 2016 2015 Accounts payable $ 134,984 $ 140,962 Accrued payroll and related costs 153,086 133,223 Accrued clinical trial expense 91,753 88,297 Accrued sales-related charges, deductions, and royalties 159,985 195,986 Income taxes payable 235,776 — Other accrued expenses and liabilities 103,512 85,644 $ 879,096 $ 644,112

Deferred Revenue

Deferred Revenue	12 Months Ended
	Dec. 31, 2016
Deferred Revenue Disclosure [Abstract]
Deferred Revenue	Deferred Revenue Deferred revenue consists of the following: As of December 31, 2016 2015 Current portion: Received or receivable from Sanofi (see Note 3a) $ 115,267 $ 101,573 Received or receivable from Bayer (see Note 3b) 31,084 24,290 Received or receivable from MTPC (see Note 3c) 9,188 2,352 Received or receivable from Teva (see Note 3d) 43,122 — Received for technology license agreement (see Note 4) 23,572 23,572 Other 9,431 1,700 $ 231,664 $ 153,487 Long-term portion: Received or receivable from Sanofi (see Note 3a) $ 503,474 $ 582,664 Received or receivable from Bayer (see Note 3b) 77,028 31,926 Received or receivable from MTPC (see Note 3c) 45,940 7,059 Received or receivable from Teva (see Note 3d) 194,050 — Received for technology license agreement (see Note 4) 10,280 33,851 Other — 9,179 $ 830,772 $ 664,679

Debt

Debt	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Convertible Debt	Debt a. Convertible Debt In October 2011, the Company issued $400.0 million aggregate principal amount of 1.875% convertible senior notes (the "Notes") in a private placement. The Notes paid interest semi-annually on April 1 and October 1, and matured on October 1, 2016. The Notes were convertible, subject to certain conditions, into cash, shares of the Company's Common Stock, or a combination of cash and shares of Common Stock, at the Company's option. The Notes initial conversion price was approximately $84.02 per share. In accordance with accounting guidance for debt with conversion and other options, the Company accounted for the liability and equity components of the Notes separately. The estimated fair value of the liability component at the date of issuance was $271.1 million , and was computed based on the fair value of similar debt instruments that do not include a conversion feature. The equity component of $120.9 million was recognized as a debt discount and represents the difference between the $392.0 million of gross proceeds from the issuance of the Notes and the $271.1 million estimated fair value of the liability component at the date of issuance. The debt discount was amortized over the expected life of a similar liability without the equity component. The Company determined this expected life to be equal to the term of the Notes, resulting in an amortization period ending October 1, 2016. The effective interest rate used to amortize the debt discount was approximately 10.2% , which was based on the Company's estimated non-convertible borrowing rate as of the date the Notes were issued. In connection with the offering of the Notes in October 2011, the Company entered into convertible note hedge ("call option") and warrant transactions with multiple counterparties, including an affiliate of the initial purchaser of the Notes. The convertible note hedge covered, subject to customary anti-dilution adjustments, the number of shares of the Company's Common Stock that initially underlie the Notes, and were intended to reduce the potential dilutive impact of the conversion feature of the Notes. The convertible note hedge terminated upon the earlier of the maturity date of the Notes or the first day the Notes were no longer outstanding. The Company paid $117.5 million for the convertible note hedge, which was recorded as a reduction to additional paid-in capital. The warrants had an initial strike price of approximately $103.41 per share, could be settled in cash or shares of the Company's Common Stock, at the Company's option, and were to become exercisable at various dates during 2017. Proceeds received from the warrant transactions totaled $93.8 million and were recorded as additional paid-in capital. The original convertible note hedge and warrants were both considered indexed to the Company's Common Stock and classified as equity; therefore, the convertible note hedge and warrants were not accounted for as derivative instruments. During 2015, the Company settled conversion obligations for $166.5 million principal amount of the Company's Notes that was previously surrendered for conversion. In accordance with the terms of the Notes, the Company elected to settle these conversion obligations through a combination of cash, in an amount equal to the principal amount of the converted Notes, and shares of the Company's Common Stock in respect of any amounts due in excess thereof. Consequently, in 2015, the Company paid $166.5 million in cash and issued 1,625,113 shares of Common Stock. In addition, in 2015, the Company allocated $819.7 million of the settlement consideration provided to the Note holders to the reacquisition of the equity component of the Notes, and recognized such amount as a reduction of stockholders' equity. In 2015, the Company also recognized a $18.9 million loss on the debt extinguishment. In connection with the Note conversions in 2015, the Company also exercised a proportionate amount of its convertible note hedges, for which the Company received 1,625,088 shares of Common Stock, which was approximately equal to the number of shares the Company was required to issue to settle the non-cash portion of the related Note conversions. The Company recorded the cost of the shares received, or $136.5 million , as Treasury Stock during 2015. During 2016, the Company settled conversion obligations for $12.9 million principal amount of the Company's Notes. Consequently, in 2016, the Company paid $12.9 million in cash and issued 121,058 shares of Common Stock. In addition, the Company allocated $47.8 million of the settlement consideration provided to the Note holders to the reacquisition of the equity component of the Notes, and recognized such amount as a reduction of stockholders' equity. The loss on the debt extinguishment in connection with the Notes that were surrendered for conversion during 2016 was not material. As a result of these Note conversions, the Company also exercised a proportionate amount of its convertible note hedges during 2016, for which the Company received 121,048 shares of Common Stock, which was approximately equal to the number of shares the Company was required to issue to settle the non-cash portion of the related Note conversions. The Company recorded the cost of the shares received, or $10.2 million , as Treasury Stock during 2016. The net carrying amount of the liability component of the Notes consists of the following: As of December 31, 2016 2015 Total convertible senior notes - par $ — $ 11,154 Unamortized discount — (352 ) $ — $ 10,802 The December 31, 2015 net carrying amount of the liability component of the Notes was recorded within other current liabilities within the Company's Consolidated Balance Sheet since the Notes were due to mature on October 1, 2016. Total interest expense associated with the Notes, net of capitalized interest as applicable, consists of the following: Year Ended December 31, 2016 2015 2014 Contractual coupon interest rate $ 7 $ 544 $ 5,036 Amortization of discount and note issuance costs 150 2,818 17,821 $ 157 $ 3,362 $ 22,857 Warrant Transactions In November 2014, the Company entered into an amendment agreement with a warrant holder whereby the parties agreed to reduce a portion of the number of warrants held by the warrant holder. The Company was obligated to settle any payments due under the amendment agreement in February 2015. Given that the amendment agreement contained a conditional obligation that required settlement in cash, and the Company's obligation was indexed to the Company's share price, the Company reclassified the estimated fair value of the 493,229 warrants from additional paid-in capital to a liability in November 2014, with such liability subsequently measured at fair value with changes in fair value recognized in earnings. As a result of the warrant holder closing out a portion of its hedge position prior to December 31, 2014, the Company recorded a $59.8 million accrued liability as of December 31, 2014 and the estimated fair value of the remaining liability as of December 31, 2014 was $87.5 million , which was recorded within other current liabilities within the Company's Consolidated Balance Sheet. During the first quarter of 2015, the warrant holder closed out additional portions of its hedge position, and, as a result, in February 2015 the Company paid a total of $124.0 million to reduce the number of warrants held by such warrant holder by 416,480 . Upon expiration of the November 2014 amended agreement, in the first quarter of 2015, the remaining warrants were re-measured at fair value, and $23.3 million was reclassified back to additional paid-in capital, consistent with the original classification of the warrants under the 2011 issuance. Total losses related to changes in fair value of the warrants during the first quarter of 2015 were not material. During 2014, in addition to the November 2014 warrant agreement described above, the Company entered into agreements to reduce the number of warrants held by the warrant holders. The Company was able to settle, at its option, any payments due under the amendment agreement in cash or by delivering shares of Common Stock. Pursuant to the agreements, the Company paid an aggregate amount of $294.6 million to the warrant holders to reduce the maximum number of shares of Common Stock issuable upon exercise of the warrants by 1,220,745 in the aggregate. In November 2015, the Company entered into an amendment agreement with a warrant holder whereby the parties agreed to reduce a portion of the number of warrants held by the warrant holder. The reduction in the number of warrants was determined based on the number of warrants with respect to which the warrant holder closed out its hedge position, provided that the warrant holder did not effect any purchases at a price per share exceeding $535.00 per share, during the period starting on November 16, 2015 and ending no later than February 9, 2016 . The Company was able to settle, at its option, any payments due under the amendment agreement in cash or by delivering shares of Common Stock. As a result of the warrant holder closing out a portion of its hedge position prior to December 31, 2015, the Company paid a total of $50.0 million in 2015 to reduce the number of warrants it held by 115,970 . Additionally, during January 2016, the warrant holder closed out additional portions of its hedge position, and, as a result, the Company paid a total of $135.3 million in the first quarter of 2016 to further reduce the number of warrants held by such warrant holder by 360,406 (which was the remaining maximum number of warrants to be reduced subject to the amendment agreement). In addition to the warrant transactions described above, during 2015, the Company entered into other agreements to reduce the number of warrants held by warrant holders. The Company was able to settle, at its option, any payments due under the amendment agreement in cash or by delivering shares of Common Stock. Pursuant to the agreements, the Company paid an aggregate amount of $399.5 million to the warrant holders during 2015 to reduce the number of shares of Common Stock issuable upon exercise of the warrant by 898,547 in the aggregate. In February 2016, the Company entered into an amendment agreement with a warrant holder whereby the parties agreed to reduce a portion of the number of warrants held by the warrant holder by up to a maximum of 975,142 . The reduction in the number of warrants was determined based on the number of warrants with respect to which the warrant holder closed out its hedge position, provided that the warrant holder did not effect any purchases at a price per share exceeding $375.00 per share, during the period starting on February 22, 2016 and ending no later than May 5, 2016. The Company was able to settle, at its option, any payments due under the amendment agreement in cash or by delivering shares of Common Stock. As a result of the warrant holder closing out a portion of its hedge position, the Company paid a total of $106.9 million to reduce the number of warrants held by such warrant holder by 403,665 . In November 2016, the Company and warrant holders entered into warrant termination agreements whereby the parties agreed to cancel the remaining warrants held by the warrant holders and to terminate the respective warrant agreements in consideration for payments by the Company of $401.2 million in the aggregate. The Company made the termination payments in the fourth quarter of 2016, and, as a result, no warrants remained outstanding as of December 31, 2016. b. Credit Facility In March 2015, the Company entered into an agreement with a syndicate of lenders (the "Credit Agreement") which provides for a $750.0 million senior unsecured five -year revolving credit facility (the "Credit Facility"). The Credit Agreement includes an option for the Company to elect to increase the commitments under the Credit Facility and/or to enter into one or more tranches of term loans in the aggregate principal amount of up to $250.0 million subject to the consent of the lenders providing the additional commitments or term loans, as applicable, and certain other conditions. Proceeds of the loans under the Credit Facility may be used to finance working capital needs, and for general corporate or other lawful purposes, of Regeneron and its subsidiaries. The Credit Agreement also provides a $100.0 million sublimit for letters of credit. The Credit Agreement includes an option for the Company to elect to extend the maturity date of the Credit Facility beyond March 2020, subject to the consent of the extending lenders and certain other conditions. Amounts borrowed under the Credit Facility may be prepaid, and the commitments under the Credit Facility may be terminated, at any time without premium or penalty. Any loans under the Credit Facility have a variable interest rate based on either the London Interbank Offered Rate ("LIBOR") or an alternate base rate, plus an applicable margin that varies with the Company's debt rating and total leverage ratio. The Company had no borrowings outstanding under the Credit Facility as of December 31, 2016. The Credit Agreement contains financial and operating covenants. Financial covenants include a maximum total leverage ratio and a minimum interest expense coverage ratio. The Company was in compliance with all covenants of the Credit Facility as of December 31, 2016.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies a. Leases Descriptions of Lease Agreements The Company leases laboratory and office facilities in Tarrytown, New York (the "Tarrytown Leases"). The facilities leased by the Company in Tarrytown include (i) space in previously existing buildings, (ii) newly constructed space in two buildings ("Buildings A and B") that was completed in 2009, (iii) newly constructed space in a third building ("Building C") that was completed in 2011, (iv) under an April 2013 lease agreement, newly constructed laboratory and office space in two buildings ("Buildings D and E") that was completed in the third quarter of 2015, and (v) under a June 2015 lease agreement, an existing building ("Building F") that the Company intends to renovate for additional laboratory and office space. The lease agreements related to Buildings A, B, C, D, E, and F (collectively, the "Buildings") expire in 2029; the remaining facilities under the lease expire in June 2024. The Tarrytown Leases provide for monthly payments over their respective terms and additional charges for utilities, taxes, and operating expenses. Historically, certain of the premises under the Tarrytown Leases had been accounted for as operating leases. However, as described further below under " Facility Lease Obligations ," for the Buildings that the Company is leasing, the Company is deemed, in substance, to be the owner of the landlord's Buildings in accordance with the application of FASB authoritative guidance. On December 30, 2016, the Company entered into a Purchase Agreement with BMR-Landmark at Eastview LLC and BMR-Landmark at Eastview IV LLC (collectively, "BMR"), pursuant to which the Company agreed to purchase BMR's Tarrytown, New York facilities (the "Facility") for a purchase price of $720.0 million , subject to certain customary adjustments. The Company currently occupies a significant portion of the Facility, with the remaining rentable area, or approximately 300,000 square feet, under leases to third-party tenants. In accordance with the terms of the Purchase Agreement, the Company paid $57.0 million toward the purchase price to BMR in December 2016. The closing of the Purchase Agreement is anticipated in the first quarter of 2017. The Company intends to fund the acquisition contemplated by the Purchase Agreement with a new financing. Accordingly, the Company has entered into an engagement letter with Banc of America Leasing & Capital, LLC ("BAL"), pursuant to which BAL has been engaged to use its best efforts to arrange a $720.0 million lease financing in connection with the acquisition contemplated by the Purchase Agreement. As part of the contemplated financing, the Company intends to assign some or all its rights under the Purchase Agreement (including the right to take title to the Facility) to an affiliate of BAL at the closing of the financing, as a result of which such affiliate will become the legal owner of the Facility (the "Lessor"). Upon assignment of its rights, the Company expects to be reimbursed by BAL or an affiliate of BAL for the $57.0 million payment the Company made in December 2016. Immediately thereafter, the Company intends to lease the Facility from the Lessor for a term of five years. At the end of the lease term, the Company expects to have an option to extend the term of the lease (subject to the consent of the financing providers), purchase the Facility at a predetermined amount, or sell the Facility to a third party on behalf of the Lessor. While the Company has engaged BAL to use its best efforts to arrange a financing in connection with the contemplated Purchase Agreement, there is no guarantee that the Company will be able to obtain such financing on the agreed terms or at all. Upon entering into the Purchase Agreement with BMR, the premises under the Company's Tarrytown Leases that were historically accounted for as operating leases were deemed to be modified, as the Company now has the option to purchase the facility, under terms that make it reasonably assured to be exercised. Consequently, the leases for such premises have been re-classified as a capital lease upon execution of the Purchase Agreement, and a proportionate amount of the $57.0 million payment was recorded as reduction of the initial capital lease liability. The execution of the Purchase Agreement did not impact the balance sheet classification for the Buildings; however, a proportionate amount of the $57.0 million payment was recorded as a reduction of the existing facility lease obligation. The Company also leases certain other laboratory, office, and storage space and equipment under operating leases which expire at various times through 2022. Commitments under Operating Leases The estimated future minimum noncancelable lease commitments under operating leases, as of December 31, 2016, are as follows: Facilities Equipment Total 2017 $ 4,728 $ 5,156 $ 9,884 2018 4,860 825 5,685 2019 4,817 273 5,090 2020 4,271 12 4,283 2021 3,982 11 3,993 Thereafter 22,336 — 22,336 $ 44,994 $ 6,277 $ 51,271 Rent expense under operating leases was: Year Ended December 31, Facilities Equipment Total 2016 $ 15,861 $ 852 $ 16,713 2015 14,659 543 15,202 2014 13,360 952 14,312 Capital Leases As described above, the Company's Tarrytown Leases that had been historically accounted for as operating leases were re-classified as capital leases upon entering into the Purchase Agreement on December 30, 2016. The estimated future minimum noncancelable lease commitments under these capital leases, as of December 31, 2016, was not material as the Company anticipates closing of the Purchase Agreement in the first quarter of 2017. The Company had no additional capital leases as of December 31, 2016. At December 31, 2016, capital lease obligations of $127.3 million were included in the Company's Consolidated Balance Sheet. Facility Lease Obligations Based upon various factors, including the Company's involvement in the construction of the Buildings and its responsibility for directly paying for a substantial portion of tenant improvements, the Company is deemed, in substance, to be the owner of the landlord's Buildings in accordance with the application of FASB authoritative guidance. Consequently, in addition to capitalizing the tenant improvements, the Company capitalizes the landlord's costs of constructing these new facilities, offset by a corresponding lease obligation on the Company's Consolidated Balance Sheet. The Company also recognizes, as additional facility lease obligation, reimbursements from the Company's landlord for tenant improvement costs that the Company incurred since such payments that the Company receives from its landlord are deemed to be a financing obligation. The Company allocates a portion of its lease payments on these facilities between the Buildings and the land on which the Buildings are constructed, based on the initial estimated relative fair values of the land and Buildings. The land element of the lease is treated for accounting purposes as an operating lease. With respect to Buildings A and B, in 2009, monthly lease payments commenced and the buildings were placed in service by the Company. The imputed interest rate applicable to the Company's Buildings A and B facility lease obligation is approximately 12% . With respect to Building C, in 2011, monthly lease payments commenced and the building was placed in service by the Company. The imputed interest rate applicable to the Company's Building C facility lease obligation is approximately 11% . With respect to Buildings D and E, in 2015, monthly lease payments commenced and the buildings were placed in service by the Company. The imputed interest rate applicable to the Company's Buildings D and E facility lease obligation is approximately 7% . With respect to Building F, the building was placed in service by the Company in 2016 and monthly lease payments do not commence until 2017. The imputed interest rate applicable to the Company's Buildings F facility lease obligation is approximately 10% . In 2016, 2015, and 2014, the Company recognized $5.4 million , $9.7 million , and $14.5 million , respectively, of interest expense in connection with the Buildings' facility lease obligations. Facility lease obligations consist of the following: As of December 31, 2016 2015 Buildings A and B $ 99,323 $ 108,857 Building C 44,338 49,475 Buildings D and E 194,037 206,376 Building F 16,154 — $ 353,852 $ 364,708 The estimated future minimum noncancelable commitments under these facility lease obligations, as of December 31, 2016, exclusive of the potential impact of the closing of the Purchase Agreement (which is anticipated to occur in the first quarter of 2017), are as follows: Buildings A and B Building C Buildings D and E Building F Total 2017 $ 13,965 $ 4,740 $ 12,922 $ 490 $ 32,117 2018 14,242 4,873 13,267 759 33,141 2019 14,526 5,009 13,621 786 33,942 2020 14,818 5,149 13,983 813 34,763 2021 15,116 5,292 14,354 841 35,603 Thereafter 101,010 48,801 121,927 7,190 278,928 $ 173,677 $ 73,864 $ 190,074 $ 10,879 $ 448,494 b. Research Collaboration and Licensing Agreements As part of the Company's research and development efforts, the Company enters into research collaboration and licensing agreements with other companies and universities. These agreements contain varying terms and provisions which include fees to be paid by the Company, services to be provided, and license rights to certain proprietary technology developed under the agreements. Some of these agreements may require the Company to pay additional amounts upon the achievement of various development and commercial milestones, contingent upon the occurrence of various future events. Additionally, some of the agreements contain provisions which require the Company to pay royalties, as defined, at rates that range from 0.5% to 16.5% , in the event the Company sells or licenses any proprietary products developed under the respective agreements. The Company also has contingent reimbursement obligations to its collaborators Sanofi and Bayer once the applicable collaboration becomes profitable. See Note 3. In December 2011, the Company and Genentech, a member of the Roche Group, entered into a Non-Exclusive License and Partial Settlement Agreement (the "Original Genentech Agreement") that covered making, using, and selling EYLEA for the prevention of human eye diseases and disorders in the United States, and ended the litigation relating to those matters. Pursuant to the Original Genentech Agreement, the Company received a non-exclusive license to certain patents relating to VEGF receptor proteins, known as the Davis-Smyth patents, and other technology patents. The Original Genentech Agreement provided for the Company to make payments to Genentech based on U.S. sales of EYLEA commencing upon FDA approval of EYLEA in November 2011 through May 7, 2016. The Company made a one-time, non-refundable $60.0 million payment during 2012 upon cumulative U.S. sales of EYLEA reaching $400.0 million , and was obligated to pay royalties of 4.75% on cumulative U.S. sales of EYLEA between $400.0 million and $3.0 billion and 5.5% on any cumulative U.S sales of EYLEA over $3.0 billion . As the Company recorded net product sales of EYLEA, the Company recognized expense in connection with the Genentech Agreement using a blended mid-single digit royalty rate that reflected both the $60.0 million payment and the royalties payable on cumulative sales and that was based upon the Company's estimate of cumulative EYLEA sales through May 7, 2016. Effective May 17, 2013, the Company entered into an Amended and Restated Non-Exclusive License and Settlement Agreement with Genentech (the "Amended Genentech Agreement"), which amended the Original Genentech Agreement to include all sales of EYLEA worldwide and ended the litigation relating to those matters. Under the Amended Genentech Agreement, the Company received a worldwide non-exclusive license to the Davis-Smyth patents, and certain other patents, owned or co-owned by Genentech for the prevention or treatment of eye diseases and eye disorders in a human through administration of EYLEA to the eye. Under the Amended Genentech Agreement, the Company was obligated to make payments to Genentech based on sales of EYLEA in the United States, and EYLEA manufactured in the United States and sold outside the United States, through May 7, 2016 using the same milestone and royalty rates as in the Original Genentech Agreement. EYLEA is sold outside the United States by affiliates of Bayer under the Company's license and collaboration agreement. All payments to Genentech under the Original Genentech Agreement and the Amended Genentech Agreement were made by the Company, and Bayer shared in all such payments based on the proportion of EYLEA sales outside the United States to worldwide EYLEA sales and determined consistent with the license and collaboration agreement. The Company's obligation to pay royalties pursuant to the Original Genentech Agreement and Amended Genentech Agreement terminated on May 7, 2016, when the licenses granted to the Company thereunder became fully paid up and royalty free for the duration of the remaining term of the underlying patents. For the years ended December 31, 2016, 2015, and 2014, the Company recorded royalty expense of $125.3 million , $247.9 million , and $169.9 million , respectively, based on product sales of commercial products under various licensing agreements (including the Genentech agreements described above).

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity The Company's Restated Certificate of Incorporation, as amended, provides for the issuance of up to 40 million shares of Class A Stock, par value $0.001 per share, and 320 million shares of Common Stock (increased from 160 million shares effective upon shareholder approval obtained in 2015), par value $0.001 per share. Shares of Class A Stock are convertible, at any time, at the option of the holder into shares of Common Stock on a share-for-share basis. Holders of Class A Stock have rights and privileges identical to Common Stockholders except that each share of Class A is entitled to ten votes per share , while each share of Common Stock is entitled to one vote per share . Class A Stock may only be transferred to specified Permitted Transferees, as defined. Under the Company's Restated Certificate of Incorporation, the Company's board of directors is authorized to issue up to 30 million shares of Preferred Stock, in series, with rights, privileges, and qualifications of each series determined by the board of directors. In December 2007, Sanofi purchased 12 million newly issued, unregistered shares of the Company's Common Stock. As a condition to the closing of this transaction, Sanofi entered into an investor agreement, as amended and restated in January 2014, with the Company. Under the terms of the amended and restated investor agreement, Sanofi has three demand rights to require the Company to use all reasonable efforts to conduct a registered underwritten public offering with respect to shares of the Company's Common Stock held by Sanofi from time to time. Under the amended and restated investor agreement, Sanofi has also agreed not to dispose of any shares of the Company's Common Stock beneficially owned by Sanofi from time to time until the later of (i) December 20, 2020, and (ii) the expiration of the Antibody Discovery Agreement with Sanofi, as amended (see Note 3a) if the agreement is extended beyond December 20, 2020. These restrictions on dispositions are subject to earlier termination upon the occurrence of certain events, such as the consummation of a change-of-control transaction involving the Company or the Company's dissolution or liquidation, and certain restrictions have been imposed on the manner of sales thereafter. Further, pursuant to the amended and restated investor agreement, Sanofi is bound by certain "standstill" provisions, which contractually prohibit Sanofi from seeking to directly or indirectly exert control of the Company or acquiring more than 30% of the outstanding shares of the Company's Class A Stock and Common Stock (taken together). This prohibition will remain in place until the earliest of (i) the later of the fifth anniversaries of the expiration or earlier termination of the Company's License and Collaboration Agreement with Sanofi and the Company's ZALTRAP Agreement with Sanofi, each as amended (see Note 3a) and (ii) other specified events. Sanofi has also agreed to vote as recommended by the Company's board of directors, except that it may elect to vote proportionally with the votes cast by all of the Company's other shareholders with respect to certain change-of-control transactions, and to vote in its sole discretion with respect to liquidation or dissolution, stock issuances equal to or exceeding 20% of the outstanding shares or voting rights of the Company's Class A Stock and Common Stock (taken together), and new equity compensation plans or amendments if not materially consistent with the Company's historical equity compensation practices. The rights and restrictions under the investor agreement are subject to termination upon the occurrence of certain events. In addition, upon Sanofi reaching 20% ownership of the Company's outstanding shares of Class A Stock and Common Stock (taken together) during 2014, the Company was required to appoint an individual agreed upon by the Company and Sanofi to the Company's board of directors. This individual is required to be independent of the Company, and not to be a current or former officer, director, employee, or paid consultant of Sanofi. In connection with the Company's license and collaboration agreements with Bayer for the joint development and commercialization outside the United States of antibody product candidates to PDGFR-beta and Ang2 (see Note 3b), Bayer is bound by certain "standstill" provisions, which contractually prohibit Bayer from seeking to influence the control of the Company or acquiring more than 20% of the Company's outstanding shares of Class A Stock and Common Stock (taken together). With respect to each of these agreements, this prohibition will remain in place until the earliest of (i) the fifth anniversary of the expiration or earlier termination of the agreement or (ii) other specified events. Further, pursuant to the 2016 Teva Collaboration Agreement, Teva and its affiliates are bound by certain "standstill" provisions, which contractually prohibit them from seeking to directly or indirectly exert control of the Company or acquiring more than 5% of the Company's Class A Stock and Common Stock (taken together). This prohibition will remain in place until the earliest of (i) the fifth anniversary of the expiration or earlier termination of the agreement; (ii) the Company's announcement recommending acceptance by the Company's shareholders of a tender offer or exchange offer that, if consummated, would constitute a change of control involving the Company; (iii) the public announcement of any definitive agreement providing for a change of control involving the Company; (iv) the acquisition of more than 30% of the voting power of the Company's then outstanding Class A Stock and Common Stock (taken together); (v) the date of any issuance of shares of capital stock by the Company that would result in another party having more than 10% of the voting power of the Company's then outstanding Class A Stock and Common Stock (taken together) unless such party enters into a standstill agreement containing certain terms substantially similar to the standstill obligations of Teva; or (vi) other specified events, such as a liquidation or dissolution of the Company. In October 2011, the Company completed a private placement of $400.0 million aggregate principal amount of Notes, which were convertible into shares of the Company's Common Stock. In connection with the offering of the Notes in October 2011, the Company entered into convertible note hedge and warrant transactions. During 2016, 2015, and 2014, the Company elected to settle Notes which were surrendered for conversion through a combination of cash, in an amount equal to the principal amount of the converted Notes, and shares of the Company's Common Stock in respect of any amounts due in excess thereof. A portion of the settlement consideration provided to the Note holders was allocated to the reacquisition of the equity component of the Notes. In addition, as a result of the Note conversions, the Company exercised a proportionate amount of its convertible note hedges, for which the Company received shares of Common Stock. The shares received were recorded as Treasury Stock, at cost. See Note 11. During 2016, 2015, and 2014, the Company entered into agreements and made payments to reduce the number of warrants held by warrant holders. In addition, in November 2014, the Company entered into an amendment agreement with a warrant holder whereby the parties agreed to reduce a portion of the number of warrants held by the warrant holder. Given that the November 2014 amendment agreement contained a conditional obligation that required settlement in cash, and the Company's obligation was indexed to the Company's share price, the Company reclassified the estimated fair value of the warrants from additional paid-in capital to a liability in November 2014. See Note 11.

Long-Term Incentive Plans

Long-Term Incentive Plans	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Long-Term Incentive Plans	Long-Term Incentive Plans During 2000, the Company established the Regeneron Pharmaceuticals, Inc. 2000 Long-Term Incentive Plan which, as amended and restated and approved by the Company's shareholders (the "2000 Incentive Plan"), provided for the issuance of up to 35,397,043 shares of Common Stock in respect of awards, in addition to any shares subject to awards that were returned to the 2000 Incentive Plan upon expiration, forfeiture, surrender, exchange, cancellation, or termination of previously granted awards. During 2014, the Company established, and the Company's shareholders approved, the Regeneron Pharmaceuticals, Inc. 2014 Long-Term Incentive Plan (the "2014 Incentive Plan"). As of the shareholder approval date, the 2014 Incentive Plan provides for the issuance of up to 16,485,333 shares of Common Stock in respect of awards (including 4,485,333 shares of Common Stock rolled over into the 2014 Incentive Plan from the 2000 Incentive Plan), which were registered with the Securities and Exchange Commission, in addition to any shares subject to awards under the 2000 Incentive Plan or the 2014 Incentive Plan that are added to the pool of shares available for grant under the 2014 Incentive Plan upon the expiration, forfeiture, surrender, exchange, cancellation, or termination of previously granted awards. Employees of the Company, including officers, and nonemployees, including consultants and nonemployee members of the Company's board of directors (collectively, "Participants"), may receive awards as determined by a committee of independent directors ("Committee"). The awards that may be made under the 2014 Incentive Plan include: (a) Incentive Stock Options ("ISOs") and Nonqualified Stock Options, (b) shares of Restricted Stock, (c) shares of Phantom Stock, (d) Stock Bonuses, and (e) Other Awards. Stock Option awards grant Participants the right to purchase shares of Common Stock at prices determined by the Committee; however, in the case of an ISO, the option exercise price may not be less than the fair market value of a share of Common Stock on the date the option is granted. Options vest over a period of time determined by the Committee, generally on a pro rata basis over a three - to four -year period. The Committee also determines the expiration date of each option; however, no ISO is exercisable more than ten years after the date of grant. The maximum term of options that have been awarded under the 2000 Incentive Plan or 2014 Incentive Plan (collectively, the "Incentive Plans") is ten years. Restricted Stock awards grant Participants shares of restricted Common Stock or allow Participants to purchase such shares at a price determined by the Committee. Such shares are nontransferable for a period determined by the Committee ("vesting period"). Should employment terminate, as specified in the Incentive Plans, except as determined by the Committee in its discretion and subject to the applicable Incentive Plan documents, the ownership of any unvested Restricted Stock will be transferred to the Company. In such an event, the Company will be obligated to repay the Participant the amount, if any, paid by the Participant for such shares. In addition, if the Company requires a return of the Restricted Stock, it also has the right to require a return of all dividends paid on such shares. Phantom Stock awards provide the Participant the right to receive, within 30 days of the date on which the share vests, an amount, in cash and/or shares of Common Stock as determined by the Committee, equal to the sum of the fair market value of a share of Common Stock on the date such share of Phantom Stock vests and the aggregate amount of cash dividends paid with respect to a share of Common Stock during the period from the grant date of the share of Phantom Stock to the date on which the share vests. Stock Bonus awards are bonuses payable in shares of Common Stock which are granted at the discretion of the Committee. Other Awards are other forms of awards which are valued based on the Common Stock. Subject to the provisions of the 2014 Incentive Plan, the terms and provisions of such Other Awards are determined solely on the authority of the Committee. The Incentive Plans contain provisions that allow for the Committee to provide for the immediate vesting of awards upon a change in control of the Company, as defined in the Plans. As of December 31, 2016 , there were 6,408,989 shares available for future grants under the 2014 Incentive Plan. No additional awards may be made under the 2000 Incentive Plan. a. Stock Options Transactions involving stock option awards during 2016 under the Company's Incentive Plans are summarized in the table below. Stock Options: Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Intrinsic Value Outstanding as of December 31, 2015 23,165,769 $ 236.75 2016: Granted 4,201,978 $ 386.44 Forfeited (468,798 ) $ 398.57 Expired (20,645 ) $ 420.04 Exercised (1,742,277 ) $ 76.79 Outstanding as of December 31, 2016 25,136,027 $ 269.69 6.66 $ 3,399,815 Vested and expected to vest as of December 31, 2016 24,598,430 $ 266.16 6.60 $ 3,397,437 Exercisable as of December 31, 2016 15,140,287 $ 166.96 5.19 $ 3,299,296 The Company satisfies stock option exercises with newly issued shares of the Company's Common Stock. The total intrinsic value of stock options exercised during 2016 , 2015 , and 2014 was $550.4 million , $1,031.6 million , and $1,081.2 million , respectively. The intrinsic value represents the amount by which the market price of the underlying stock exceeds the exercise price of an option. The Company grants stock options with exercise prices that are equal to or greater than the average market price of the Company's Common Stock on the date of grant ("Market Price"). The table below summarizes the weighted-average exercise prices and weighted-average grant-date fair values of options issued during the years ended December 31, 2016 , 2015 , and 2014 . The fair value of each option granted under the Company's Incentive Plans during these periods was estimated on the date of grant using the Black-Scholes option-pricing model. Number of Options Granted Weighted-Average Exercise Price Weighted-Average Fair Value 2016: Exercise price equal to Market Price 4,201,978 $ 386.44 $ 126.68 2015: Exercise price equal to Market Price 4,495,487 $ 537.29 $ 181.65 2014: Exercise price equal to Market Price 3,913,368 $ 385.33 $ 140.38 For the years ended December 31, 2016 , 2015 , and 2014 , the Company recognized $546.0 million , $443.7 million , and $306.1 million , respectively, of non-cash stock-based compensation expense related to non-performance based stock option awards. As of December 31, 2016 , there was $888.0 million of stock-based compensation cost related to outstanding non-performance based stock options, net of estimated forfeitures, which had not yet been recognized. The Company expects to recognize this compensation cost over a weighted-average period of 1.9 years. For the year ended December 31, 2014 , the Company recognized $4.1 million of non-cash stock-based compensation expense related to performance-based options. The Company has not issued any performance-based options since 2011, and such options became fully vested during 2014. Fair Value Assumptions: The following table summarizes the weighted average values of the assumptions used in computing the fair value of option grants during 2016, 2015, and 2014. 2016 2015 2014 Expected volatility 34 % 35 % 39 % Expected lives from grant date 5.1 years 5.1 years 5.2 years Expected dividend yield 0 % 0 % 0 % Risk-free interest rate 1.84 % 1.68 % 1.62 % Expected volatility has been estimated based on actual movements in the Company's stock price over the most recent historical periods equivalent to the options' expected lives. Expected lives are principally based on the Company's historical exercise experience with previously issued employee and board of directors' option grants. The expected dividend yield is zero as the Company has never paid dividends and does not currently anticipate paying any in the foreseeable future. The risk-free interest rates are based on quoted U.S. Treasury rates for securities with maturities approximating the options' expected lives. b. Restricted Stock A summary of the Company's activity related to Restricted Stock awards during 2016 is summarized below: Restricted Stock: Number of Shares Weighted-Average Grant Date Fair Value Outstanding as of December 31, 2015 541,700 $ 133.96 2016: Granted 16,750 $ 385.84 Vested (11,590 ) $ 125.38 Forfeited (40 ) $ 237.68 Outstanding as of December 31, 2016 546,820 $ 141.85 The Company recognized non-cash stock-based compensation expense from Restricted Stock awards of $13.9 million , $15.3 million , and $11.5 million in 2016 , 2015 , and 2014 , respectively. As of December 31, 2016, there was $26.0 million of stock-based compensation cost related to unvested shares of Restricted Stock which had not yet been recognized. The Company expects to recognize this compensation cost over a weighted-average period of 1.2 years.

Employee Savings Plan

Employee Savings Plan	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Employee Savings Plan	Employee Savings Plans The Company maintains the Regeneron Pharmaceuticals, Inc. 401(k) Savings Plan (the "Savings Plan"). The terms of the Savings Plan, as amended and restated, allow U.S. employees (as defined by the Savings Plan) to contribute to the Savings Plan a percentage of their compensation. In addition, the Company may make discretionary contributions ("Contribution"), as defined, to the accounts of participants under the Savings Plan. The Company recognized $17.7 million , $15.4 million , and $13.1 million of Contribution expense in 2016, 2015, and 2014, respectively. In 2014, the Regeneron Ireland Pension Plan (the "Ireland Plan"), a defined contribution occupational pension plan which covers all eligible Ireland-based employees (as defined by the Ireland Plan), was established. Contributions to the Ireland Plan are comprised of two components: (i) a minimum mandatory employee and employer contribution rate, and (ii) a matching scheme, whereby the Company will match employee contributions up to a certain percentage. Employees can make additional voluntary contributions to the Ireland Plan. Expenses related to the Company's contributions to the Ireland Plan were not material during 2016, 2015, and 2014.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is subject to U.S. federal, state, and foreign income taxes. Components of income before income taxes consist of the following: Year Ended December 31, 2016 2015 2014 United States $ 1,650,959 $ 1,665,087 $ 1,101,446 Foreign (321,144 ) (439,990 ) (340,211 ) $ 1,329,815 $ 1,225,097 $ 761,235 Components of income tax expense consist of the following: Year Ended December 31, 2016 2015 2014 Current: Federal $ 786,964 $ 686,561 $ 437,038 State 8,769 28,568 28,718 Foreign (1,362 ) 4,004 2,879 Total current tax expense 794,371 719,133 468,635 Deferred: Federal (377,368 ) (119,849 ) (62,932 ) State 13,431 (3,768 ) 18,891 Foreign 3,859 (6,475 ) (1,485 ) Total deferred tax (benefit) expense (360,078 ) (130,092 ) (45,526 ) $ 434,293 $ 589,041 $ 423,109 In 2015 and 2014, the Company utilized $405.3 million and $439.3 million of excess tax benefits in connection with stock option exercises, which were credited to additional paid-in capital as realized. The Company elected to early adopt ASU 2016-09 during the second quarter of 2016. Consequently, in 2016, the Company recorded excess tax benefits of $144.8 million within income tax expense. See Note 1. "Business Overview and Summary of Significant Accounting Policies - Recently Issued Accounting Standards. " The Company also recorded an income tax benefit in its Statement of Comprehensive Income of $3.3 million during the year ended December 31, 2016 and an income tax provision of $24.9 million and $27.1 million during the years ended December 31, 2015 and 2014, respectively, primarily related to unrealized gains (losses) on available-for-sale marketable securities. A reconciliation of the U.S. statutory income tax rate to the Company's effective income tax rate is as follows: Year Ended December 31, 2016 2015 2014 U.S. federal statutory tax rate 35.0 % 35.0 % 35.0 % Stock-based compensation (10.9 ) — — State and local income taxes 0.3 1.0 2.4 Change in state effective rate 1.0 (0.1 ) 2.9 Foreign income tax rate differential 8.8 12.2 15.8 Income tax credits (1.2 ) (1.6 ) (5.1 ) Non-deductible Branded Prescription Drug Fee 1.9 2.0 2.8 Domestic production activities deduction (2.8 ) (3.2 ) — Other permanent differences 0.6 2.8 1.8 Effective income tax rate 32.7 % 48.1 % 55.6 % In 2016, the difference between the U.S. federal statutory rate of 35% and the Company's effective tax rate of 32.7% was primarily attributable to the tax benefit associated with stock-based compensation, the domestic manufacturing deduction, and the federal tax credit for research activities, offset by the negative impact of losses incurred in foreign jurisdictions with rates lower than the U.S. federal statutory rate and the non-tax deductible Branded Prescription Drug Fee. In 2015, the difference between the U.S. federal statutory rate of 35% and the Company's effective tax rate of 48.1% was primarily attributable to losses incurred in foreign jurisdictions with rates lower than the U.S. federal statutory rate, partly offset by the positive impact of the domestic manufacturing deduction. In 2014, the difference between the U.S. federal statutory rate of 35% and the Company's effective tax rate of 55.6% was primarily attributable to losses incurred in foreign jurisdictions with rates lower than the U.S. federal statutory rate and the non-deductible Branded Prescription Drug Fee, partly offset by the positive impact of the federal tax credit for increased research activities and state income tax credits. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company's deferred tax assets and liabilities are as follows: As of December 31, 2016 2015 Deferred tax assets: Net operating loss carryforward $ 137 $ 140 Fixed and intangible assets 21,139 — Deferred revenue 214,587 51,766 Deferred compensation 515,984 349,508 Capitalized research and development costs 2,492 7,725 Accrued expenses 37,188 47,520 Other 46,471 26,580 837,998 483,239 Valuation allowance (3,420 ) — Total deferred tax assets 834,578 483,239 Deferred tax liabilities: Unrealized gains/losses on marketable securities — (3,280 ) Fixed assets and intangible assets — (5,559 ) Other (9,275 ) (12,455 ) Total deferred tax liabilities (9,275 ) (21,294 ) Net deferred tax assets $ 825,303 $ 461,945 The Company's 2012 through 2015 federal income tax returns remain open to examination by the IRS. The Company's 2012 federal income tax return is currently under audit by the IRS. The Company's state income tax returns from 2013 to 2015 remain open to examination. The Department of Revenue of the Commonwealth of Pennsylvania is currently auditing the Company's 2013 and 2014 tax returns . The United States and many states generally have statutes of limitation ranging from 3 to 5 years; however, those statutes could be extended due to the Company's net operating loss and tax credit carryforward positions in a number of the Company's tax jurisdictions. In general, tax authorities have the ability to review income tax returns for loss periods in which the statute of limitation has previously expired to adjust the net operating loss carryforward or tax credits generated in those years. The following table summarizes the gross amounts of unrecognized tax benefits. The amount of unrecognized tax benefits that, if settled, would impact the effective tax rate is $107.2 million , $102.1 million , and $51.2 million as of December 31, 2016, 2015, and 2014, respectively. 2016 2015 2014 Balance as of January 1 $ 116,572 $ 57,615 $ 26,627 Gross increases related to current year tax positions 45,575 59,909 27,538 Gross (decreases) increases related to prior year tax positions (42,284 ) (952 ) 6,464 Gross decrease due to settlements, recapture, filed returns, and lapse of statutes of limitation (2,697 ) — (3,014 ) Balance as of December 31 $ 117,166 $ 116,572 $ 57,615 In 2016 and 2015, the increases in unrecognized tax benefits related primarily to the Company's calculation of certain tax credits and other items related to the Company's international operations. In 2014, the decreases in unrecognized tax benefits resulted from the settlement of the IRS audit of the 2011 tax year and the New York State audit of the 2009 to 2011 tax years, as well as the reduction in the New York state income tax rate. In 2016, the Company accrued interest of $3.3 million related to its unrecognized tax benefits. In 2015 and 2014, accrued interest related to unrecognized tax benefits recorded by the Company was not material. The Company believes that it is reasonably possible that its unrecognized tax benefits as of December 31, 2016 may decrease by up to $22.3 million within the next twelve months related to the resolution of state tax exposures.

Legal Matters

Legal Matters	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Legal Matters	Legal Matters From time to time, the Company is a party to legal proceedings in the course of the Company's business. Costs associated with the Company's involvement in legal proceedings are expensed as incurred. The outcome of any such proceedings, regardless of the merits, is inherently uncertain. If the Company were unable to prevail in any such proceedings, its consolidated financial position, results of operations, and future cash flows may be materially impacted. Proceedings Relating to '287 Patent, '163 Patent, and '018 Patent The Company is a party to patent infringement litigation initiated by the Company involving its European Patent No. 1,360,287 (the "'287 Patent"), its European Patent No. 2,264,163 (the "'163 Patent"), and its U.S. Patent No. 8,502,018 (the "'018 Patent"). Each of these patents concerns genetically engineered mice capable of producing chimeric antibodies that are part human and part mouse. Chimeric antibody sequences can be used to produce high-affinity fully human monoclonal antibodies. In these proceedings, the Company claims infringement of several claims of the '287 Patent, the '163 Patent, and the '018 Patent (as applicable), and seeks, among other types of relief, an injunction and an account of profits in connection with the defendants' infringing acts, which may include, among other things, the making, use, keeping, sale, or offer for sale of genetically engineered mice (or certain cells from which they are derived) that infringe one or more claims of the '287 Patent, the '163 Patent, and the '018 Patent (as applicable). At this time, the Company is not able to predict the outcome of, or estimate possible gain or a range of possible loss, if any, related to, these proceedings. Proceedings Relating to Praluent (alirocumab) Injection As described in greater detail below, the Company is currently a party to patent infringement actions initiated by Amgen Inc. against the Company and Sanofi (and/or the Company's and Sanofi's respective affiliated entities) in a number of jurisdictions relating to Praluent, which the Company is jointly developing and commercializing with Sanofi. In the United States, Amgen has asserted a number of U.S. patents, which were subsequently narrowed to U.S. Patent Nos. 8,829,165 (the "'165 Patent") and 8,859,741 (the "'741 Patent"), and seeks a permanent injunction to prevent the Company and the Sanofi defendants from manufacturing, using, offering to sell, or selling within the United States (as well as importing into the United States) (collectively, "Commercializing") Praluent. Amgen also seeks a judgment of patent infringement of the asserted patents, monetary damages (together with interest), costs and expenses of the lawsuits, and attorneys' fees. A jury trial in this litigation was held in the United States District Court for the District of Delaware from March 8 to March 16, 2016. During the course of the trial, the court ruled as a matter of law in favor of Amgen that the asserted patent claims were not obvious, and in favor of the Company and the Sanofi defendants that there was no willful infringement of the asserted patent claims by the Company or the Sanofi defendants. On March 16, 2016, the jury returned a verdict in favor of Amgen, finding that the asserted claims of the '165 and '741 Patents were not invalid based on either a lack of written description or a lack of enablement. On January 3, 2017, the court issued a final opinion and judgment, denying the Company and the Sanofi defendants' motions for new trial and judgment as a matter of law. The court also denied as moot Amgen's motion to strike the Company and the Sanofi defendants' request to obtain a judgment as a matter of law, which allows the U.S. Court of Appeals for the Federal Circuit to address the Company and the Sanofi defendants' patent invalidity arguments on appeal. On January 12, 2017, the Company and the Sanofi defendants filed a notice of appeal with the U.S. Court of Appeals for the Federal Circuit. On January 18, 2017, the U.S. Court of Appeals for the Federal Circuit ordered an expedited briefing schedule of the appeal on the merits, pursuant to which the briefing is scheduled to be completed no later than March 31, 2017. On January 31, 2017, Amgen filed a motion with the United States District Court for the District of Delaware to amend the court's final judgment to include an award of supplemental damages (including interest) and enhancement of such damages following the resolution of the appeal. On March 23 and March 24, 2016, the United States District Court for the District of Delaware held a permanent injunction hearing to determine whether Regeneron and the Sanofi defendants should be prohibited from Commercializing Praluent in the United States. On January 5, 2017, the court granted the permanent injunction but delayed its imposition for 30 days (subsequently extended to 45 days) from the date of grant (i.e., until February 21, 2017). On January 13, 2017, the Company and the Sanofi defendants filed an emergency motion for stay of the permanent injunction pending appeal with the U.S. Court of Appeals for the Federal Circuit; and, on February 8, 2017, the court granted the stay pending appeal. On July 25, 2016, Amgen filed a lawsuit against Regeneron, Sanofi-Aventis Groupe S.A., Sanofi-Synthelabo Limited, Aventis Pharma Limited, Sanofi Winthrop Industrie S.A., and Sanofi-Aventis Deutschland GmbH in the English High Court of Justice, Chancery Division, Patents Court, in London, seeking a declaration of infringement of Amgen's European Patent No. 2,215,124 (the "'124 Patent"), which pertains to PCSK9 monoclonal antibodies, by Praluent. The lawsuit also seeks a permanent injunction, damages, an accounting of profits, and costs and interest. On February 8, 2017, the court temporarily stayed this litigation on terms mutually agreed by the parties. Also on July 25, 2016, Amgen filed a lawsuit for infringement of the '124 Patent against Regeneron, Sanofi-Aventis Groupe S.A., Sanofi Winthrop Industrie S.A., and Sanofi-Aventis Deutschland GmbH in the Regional Court of Düsseldorf, Germany, seeking a permanent injunction, an accounting of marketing activities, a recall of Praluent and its removal from distribution channels, and damages. Oral hearing on this infringement lawsuit is currently scheduled for October 19, 2017. On September 26, 2016, Amgen filed a lawsuit for infringement of the '124 Patent in the Tribunal de grande instance in Paris, France against Regeneron, Sanofi-Aventis Groupe S.A., and Sanofi Winthrop Industrie. Amgen is seeking the prohibition of allegedly infringing activities with a €10,000 penalty per drug unit of Praluent produced in violation of the court order sought by Amgen; an appointment of an expert for the assessment of damages; disclosure of technical (including supply-chain) and accounting information to the expert and the court; provisional damages of €10.0 million (which would be awarded on an interim basis pending final determination); reimbursement of costs; publication of the ruling in three newspapers; and provisional enforcement of the decision to be issued, which would ensure enforcement of the decision (including any provisional damages) pending appeal. Amgen is not seeking a preliminary injunction in this proceeding at this time. At this time, the Company is not able to predict the outcome of, or estimate a range of possible loss, if any, related to these proceedings. Proceedings Relating to Patents Owned by Genentech and City of Hope On July 27, 2015, the Company and Sanofi-Aventis U.S. LLC ("Sanofi-Aventis") filed a complaint in the United States District Court for the Central District of California (Western Division) seeking a declaratory judgment of invalidity, as well as non-infringement by the manufacture, use, sale, offer of sale, or importation of Praluent, of U.S. Patent No. 7,923,221 (the "'221 Patent") jointly owned by Genentech, Inc. ("Genentech") and City of Hope relating to the production of recombinant antibodies by host cells. On the same day, the Company and Sanofi-Aventis initiated an inter partes review in the United States Patent and Trademark Office ("USPTO") seeking a declaration of invalidity of certain claims of U.S. Patent No. 6,331,415 (the "'415 Patent" and, together, with the "221 Patent", the "Cabilly Patents") jointly owned by Genentech and City of Hope relating to the production of recombinant antibodies by host cells. On February 5, 2016, the USPTO instituted an inter partes review of the validity of most of the patent claims of the '415 Patent for which review had been requested. On August 18, 2016, Regeneron and Sanofi-Aventis entered into a License and Settlement Agreement with Genentech and City of Hope that resolved all outstanding issues concerning the Cabilly Patents in the above-referenced litigation and inter partes review proceeding, resulting in a joint stipulation of dismissal being entered in the court and the USPTO. Under the agreement, Regeneron has been granted a license to the Cabilly Patents to make, use, and sell Praluent and all other antibody products under development at the time of the settlement. Proceedings Relating to Shareholder Derivative Claims On December 30, 2015, an alleged shareholder filed a shareholder derivative complaint in the New York Supreme Court, naming the current and certain former non-employee members of the Company's board of directors, the Chairman of the board of directors, the Company's Chief Executive Officer, and the Company's Chief Scientific Officer as defendants and Regeneron as a nominal defendant. The complaint asserts that the individual defendants breached their fiduciary duties and were unjustly enriched when they approved and/or received allegedly excessive compensation in 2013 and 2014. The complaint seeks damages in favor of the Company for the alleged breaches of fiduciary duties and unjust enrichment; changes to Regeneron's corporate governance and internal procedures; invalidation of the 2014 Incentive Plan with respect to the individual defendants' compensation and a shareholder vote regarding the individual defendants' equity compensation; equitable relief, including an equitable accounting with disgorgement; and award of the costs of the action, including attorneys' fees. On March 2, 2016, the defendants filed a motion to dismiss the shareholder derivative complaint. On August 16, 2016, the court heard oral argument on defendants' motion to dismiss. On or about December 15, 2015, the Company received a shareholder litigation demand upon the Company's board of directors made by a purported Regeneron shareholder. The demand asserts that the current and certain former non-employee members of the board of directors and the Chairman of the board of directors excessively compensated themselves in 2013 and 2014. The demand requests that the board of directors investigate and bring legal action against these directors for breach of fiduciary duty, unjust enrichment, and corporate waste, and implement internal controls and systems designed to prohibit and prevent similar actions in the future. The Company's board of directors, working with outside counsel, investigated the allegations in the demand and the shareholder derivative complaint, and has determined to defer its decision on the demand until the court rules on the pending motion to dismiss the shareholder derivative complaint, as discussed above. At this time, the Company is not able to predict the outcome of, or estimate a range of possible loss, if any, relating to these matters. Department of Justice Investigation In January 2017, the Company received a subpoena from the U.S. Attorney's Office for the District of Massachusetts requesting documents relating to its support of 501(c)(3) organizations that provide financial assistance to patients; documents concerning its provision of financial assistance to patients with respect to products sold or developed by Regeneron (including EYLEA, Praluent, ARCALYST, and ZALTRAP); and certain other related documents and communications. The Company is cooperating with this investigation. The Company cannot predict the outcome or duration of these investigations or any other legal proceedings or any enforcement actions or other remedies that may be imposed on the Company arising out of these investigations.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Net Income Per Share The Company's basic net income per share amounts have been computed by dividing net income by the weighted average number of shares of Common Stock and Class A Stock outstanding. Net income per share is presented on a combined basis, inclusive of Common Stock and Class A Stock outstanding, as each class of stock has equivalent economic rights. Diluted net income per share includes the potential dilutive effect of other securities as if such securities were converted or exercised during the period, when the effect is dilutive. The calculations of basic and diluted net income per share are as follows: Year Ended December 31, 2016 2015 2014 Net income - basic $ 895,522 $ 636,056 $ 338,126 Effect of dilutive securities: Convertible senior notes - interest expense related to contractual coupon interest rate and amortization of discount and note issuance costs 397 — — Net income - diluted $ 895,919 $ 636,056 $ 338,126 (Shares in thousands) Weighted average shares - basic 104,719 103,061 100,612 Effect of dilutive securities: Stock options 10,177 9,446 9,440 Restricted stock 474 477 425 Convertible senior notes 61 — — Warrants 936 2,246 2,936 Dilutive potential shares 11,648 12,169 12,801 Weighted average shares - diluted 116,367 115,230 113,413 Net income per share - basic $ 8.55 $ 6.17 $ 3.36 Net income per share - diluted $ 7.70 $ 5.52 $ 2.98 Shares which have been excluded from diluted per share amounts because their effect would have been antidilutive, include the following: Year Ended December 31, (Shares in thousands) 2016 2015 2014 Stock options 8,041 1,343 1,470 Restricted stock 19 — — Convertible senior notes — 994 4,247

Statement of Cash Flows

Statement of Cash Flows	12 Months Ended
	Dec. 31, 2016
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Statement of Cash Flows	Statement of Cash Flows Supplemental disclosure of non-cash investing and financing activities: Included in accounts payable and accrued expenses as of December 31, 2016, 2015, and 2014 were $28.2 million , $50.7 million , and $56.2 million , respectively, of accrued capital expenditures. Included in accounts payable and accrued expenses as of December 31, 2014 was $59.8 million related to the Company's payment obligation for a reduction in the number of warrants based on a warrant holder closing out a portion of its hedge position (see Note 11). Additionally, included within other current liabilities as of December 31, 2014 was $87.5 million in connection with the estimated fair value of the remaining warrant liability (see Note 11). There were no such liabilities recorded in connection with warrants as of December 31, 2016 and 2015. The Company recognized an additional facility lease obligation of $16.8 million , $26.0 million , and $127.8 million during 2016, 2015, and 2014, respectively, in connection with capitalizing, on the Company's books, the landlord's costs of constructing new facilities that the Company has leased (see Note 12a). In addition, during 2016, the Company recognized capital lease obligations of $138.1 million in connection with the modification of the Company's Tarrytown Leases (see Note 12a).

Unaudited Quarterly Results

Unaudited Quarterly Results	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Unaudited Quarterly Results	Unaudited Quarterly Results Summarized quarterly financial data for the years ended December 31, 2016 and 2015 are set forth in the following tables. First Quarter Ended March 31, 2016 * Second Quarter Ended June 30, 2016 Third Quarter Ended September 30, 2016 Fourth Quarter Ended December 31, 2016 (Unaudited) Revenues $ 1,200,849 $ 1,212,629 $ 1,220,122 $ 1,226,827 Net income $ 181,385 $ 196,218 $ 264,804 $ 253,115 Net income per share - basic $ 1.74 $ 1.88 $ 2.53 $ 2.41 Net income per share - diluted $ 1.59 $ 1.69 $ 2.27 $ 2.19 First Quarter Ended March 31, 2015 Second Quarter Ended June 30, 2015 Third Quarter Ended September 30, 2015 Fourth Quarter Ended December 31, 2015 (Unaudited) Revenues $ 869,612 $ 998,617 $ 1,137,422 $ 1,098,077 Net income $ 76,021 $ 194,643 $ 210,398 $ 154,994 Net income per share - basic $ 0.74 $ 1.89 $ 2.04 $ 1.49 Net income per share - diluted $ 0.66 $ 1.69 $ 1.82 $ 1.34 * Due to the adoption of ASU 2016-09, the Company revised its net income from the amounts originally reported for the quarterly period ended March 31, 2016 to include a $15.6 million income tax benefit, which was originally recorded as additional paid-in capital.

Business Overview and Summary27

Business Overview and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Consolidation	Basis of Presentation The consolidated financial statements include the accounts of Regeneron and its wholly-owned subsidiaries. Intercompany balances and transactions are eliminated in consolidation. Certain reclassifications have been made to prior period amounts to conform with the current period's presentation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles 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. Estimates which could have a significant impact on the Company's financial statements include provisions related to product sales, such as rebates, chargebacks, and distribution-related fees; periods over which payments, including non-refundable up-front, license, and milestone payments, are recognized as revenue in connection with collaboration and other agreements; periods over which certain clinical trial costs are recognized; fair value of stock options; inventory that may expire prior to expected sale or has a cost basis in excess of its estimated realizable value; capitalization of inventory costs associated with the Company's products prior to regulatory approval; provisions for loss contingencies; deferred tax asset valuation allowances; and the assessment of uncertain tax positions. With respect to the Company's collaborations with Sanofi and Bayer: • Included in Sanofi collaboration revenue is the Company's share of profits or losses from commercialization of antibodies, which is provided by Sanofi, and includes an estimate of the Company's share of profits or losses for the most recent fiscal quarter. • Included in Bayer collaboration revenue is the Company's share of profits or losses from commercialization of EYLEA outside the United States, which is provided by Bayer, and includes an estimate of the Company's share of profits or losses for the most recent fiscal quarter. • Included in research and development expenses is the Company's share of development expenses incurred by Bayer and Sanofi, including the Company's share of Bayer and Sanofi estimated development expenses for the most recent fiscal quarter. These estimates for the most recent period are adjusted on a prospective basis, if necessary, in the subsequent period to reflect actual amounts.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid debt instruments with a maturity of three months or less when purchased to be cash equivalents. The carrying amount reported in the Consolidated Balance Sheet for cash and cash equivalents approximates its fair value.
Marketable Securities	Marketable Securities The Company has an investment policy that includes guidelines on acceptable investment securities, minimum credit quality, maturity parameters, and concentration and diversification. The Company invests its excess cash primarily in marketable securities issued by investment grade institutions. The Company considers its marketable securities to be "available-for-sale," as defined by authoritative guidance issued by the Financial Accounting Standards Board ("FASB"). These assets are carried at fair value and the unrealized gains and losses are included in accumulated other comprehensive income (loss). Realized gains and losses on marketable securities are included as a component of other income (expense), net. The Company reviews its portfolio of marketable securities, using both quantitative and qualitative factors, to determine if declines in fair value below cost are other-than-temporary. If a decline in the fair value of a marketable security in the Company's investment portfolio is deemed to be other-than-temporary, the Company writes down the cost basis of the security to its current fair value and recognizes a loss as a charge against income.
Accounts Receivable - Trade	Accounts Receivable - Trade The Company's trade accounts receivable arise from product sales and represent amounts due from its distributors and specialty pharmacies (collectively, the Company's "customers"), which are all located in the United States. The Company monitors the financial performance and credit worthiness of its large customers so that it can properly assess and respond to changes in their credit profile. The Company provides reserves against trade receivables for estimated losses, if any, that may result from a customer's inability to pay. Amounts determined to be uncollectible are written-off against the reserve.
Inventories	Inventories Inventories are stated at the lower of cost or estimated realizable value. The Company determines the cost of inventory using the first-in, first-out, or FIFO, method. The Company capitalizes inventory costs associated with the Company's products prior to regulatory approval when, based on management's judgment, future commercialization is considered probable and the future economic benefit is expected to be realized; otherwise, such costs are expensed as research and development. The determination to capitalize inventory costs is based on various factors, including status and expectations of the regulatory approval process, any known safety or efficacy concerns, potential labeling restrictions, and any other impediments to obtaining regulatory approval. The Company periodically analyzes its inventory levels to identify inventory that may expire prior to expected sale or has a cost basis in excess of its estimated realizable value, and writes-down such inventories as appropriate. In addition, the Company's products are subject to strict quality control and monitoring which the Company performs throughout the manufacturing process. If certain batches or units of product no longer meet quality specifications or become obsolete due to expiration, the Company records a charge to cost of goods sold to write down such unmarketable inventory to its estimated realizable value.
Property, Plant and Equipment	Property, Plant, and Equipment Property, plant, and equipment are stated at cost, net of accumulated depreciation. Depreciation is provided on a straight-line basis over the estimated useful lives of the assets. Leasehold improvements are amortized over the shorter of the estimated useful lives of the assets or the lease term. Costs of construction of certain long-lived assets include capitalized interest, which is amortized over the estimated useful life of the related asset. Expenditures for maintenance and repairs which do not materially extend the useful lives of the assets are charged to expense as incurred. The cost and accumulated depreciation or amortization of assets retired or sold are removed from the respective accounts, and any gain or loss is recognized in operations. The estimated useful lives of property, plant, and equipment are as follows: Building and improvements 10-40 years Laboratory and other equipment 3-10 years Furniture and fixtures 5 years The Company periodically assesses the recoverability of long-lived assets, such as property, plant, and equipment, and evaluates such assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.
Revenue Recognition - Product Revenue	Product Revenue Product revenue consists of U.S. sales of EYLEA and ARCALYST. Revenue from product sales is recognized when persuasive evidence of an arrangement exists, title to product and associated risk of loss have passed to the customer, the price is fixed or determinable, collection from the customer is reasonably assured, the Company has no further performance obligations, and returns can be reasonably estimated. The Company's written contracts with its customers stipulate product is shipped freight on board destination (FOB destination). The Company records revenue from product sales upon delivery to its customers. The Company sells EYLEA in the United States to several distributors and specialty pharmacies. The Company sells ARCALYST in the United States to two specialty pharmacies. Under these distribution models, the distributors and specialty pharmacies generally take physical delivery of product. For EYLEA, the distributors and specialty pharmacies generally sell the product directly to healthcare providers, whereas for ARCALYST, the specialty pharmacies sell the product directly to patients. Revenue from product sales is recorded net of applicable provisions for rebates and chargebacks under governmental and other programs, distribution-related fees, and other sales-related deductions. Calculating these provisions involves estimates and judgments. The Company reviews its estimates of rebates, chargebacks, and other applicable provisions each period and records any necessary adjustments in the current period's net product sales. Government Rebates and Chargebacks: The Company estimates reductions to product sales for Medicaid and Veterans' Administration ("VA") programs, and for certain other qualifying federal and state government programs. Based upon the Company's contracts with government agencies, statutorily-defined discounts applicable to government-funded programs, historical experience, and estimated payer mix, the Company estimates and records an allowance for rebates and chargebacks. The Company's liability for Medicaid rebates consists of estimates for claims that a state will make for a current quarter, claims for prior quarters that have been estimated for which an invoice has not been received, and invoices received for claims from prior quarters that have not been paid. The Company's reserves related to discounted pricing to VA, Public Health Services ("PHS"), and other institutions (collectively "qualified healthcare providers") represent the Company's estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices the Company charges to its customers (i.e., distributors and specialty pharmacies). The Company's customers charge the Company for the difference between what they pay for the products and the ultimate selling price to the qualified healthcare providers. The Company's reserve for this discounted pricing is based on expected sales to qualified healthcare providers and the chargebacks that customers have already claimed. Distribution-Related Fees: The Company has written contracts with its customers that include terms for distribution-related fees. The Company estimates and records distribution and related fees due to its customers based on gross sales. Prompt Pay Discounts: No prompt pay discounts are currently offered to the Company's customers on sales of EYLEA. In connection with sales of ARCALYST, the Company offers discounts to its customers for prompt payments. The Company estimates these discounts based on customer terms and historical experience, and expects that its customers will always take advantage of this discount. Therefore, the Company accrues 100% of the prompt pay discount that is based on the gross amount of each ARCALYST invoice, at the time of sale. Product Returns: Consistent with industry practice, the Company offers its customers a limited right to return product purchased directly from the Company, which is principally based upon the product's expiration date. The Company will accept returns for three months prior to and up to six months after the product expiration date. Product returned is generally not resalable given the nature of the Company's products and method of administration. The Company develops estimates for product returns based upon historical experience, inventory levels in the distribution channel, shelf life of the product, and other relevant factors. The Company monitors product supply levels in the distribution channel, as well as sales by its customers of EYLEA to healthcare providers and ARCALYST to patients using product-specific data provided by its customers. If necessary, the Company's estimates of product returns may be adjusted in the future based on actual returns experience, known or expected changes in the marketplace, or other factors.
Revenue Recognition - Collaboration Revenue	Collaboration Revenue The Company earns collaboration revenue in connection with collaboration agreements to develop and commercialize product candidates and utilize the Company's technology platforms. These arrangements may require the Company to deliver various rights, services, and/or goods across the entire life cycle of a product or product candidate. The terms of these agreements typically include that consideration be provided to the Company in the form of non-refundable up-front payments, milestone payments, payments for development and commercialization activities, and sharing of profits or losses arising from the commercialization of products. In connection with non-refundable up-front payments, the Company's performance period estimates are principally based on projections of the scope, progress, and results of its research and development activities. Due to the variability in the scope of activities and length of time necessary to develop a drug product, changes to development plans as programs progress, and uncertainty in the ultimate requirements to obtain regulatory approval for commercialization, revisions to performance period estimates are likely to occur periodically, and could result in material changes to the amount of revenue recognized each year in the future. In addition, estimated performance periods may change if development programs encounter delays, or the Company and its collaborators decide to expand or contract the clinical plans for a drug candidate in various disease indications. In arrangements involving multiple deliverables, each required deliverable is evaluated to determine whether it qualifies as a separate unit of accounting. This determination is generally based on whether the deliverables in the arrangement meet certain criteria, including whether the delivered item or items has value to the collaborator on a standalone basis. The arrangement's consideration that is fixed and determinable is allocated to each separate unit of accounting based on the relative selling price of each deliverable. If multiple collaboration activities or rights do not require separation, they are combined into a single unit of accounting and recognized over the performance period, which is the period over which the Company is obligated to deliver goods or services. The Company estimates its performance period based on the specific terms of each agreement, and adjusts the performance periods, if appropriate, based on the applicable facts and circumstances. Payments which are based on achieving a specific substantive performance milestone, involving a degree of risk, are recognized as revenue when the milestone is achieved and the related payment is due and non-refundable, provided there is no future service obligation associated with that milestone. Substantive performance milestones typically consist of significant achievements in the development life-cycle of the related product candidate, such as completion of clinical trials, filing for approval with regulatory agencies, and receipt of approvals by regulatory agencies. In determining whether a payment is deemed to be a substantive performance milestone, the Company takes into consideration (i) the enhancement in value to the related development product candidate, (ii) the Company's performance and the relative level of effort required to achieve the milestone, (iii) whether the milestone relates solely to past performance, and (iv) whether the milestone payment is considered reasonable relative to all of the deliverables and payment terms. Payments for achieving milestones which are not considered substantive are deferred and recognized over the related performance period. The Company enters into collaboration agreements that include varying arrangements regarding which parties perform and bear the costs of research and development activities. The Company may share the costs of research and development activities with a collaborator, or the Company may be reimbursed for all or a significant portion of the costs of the Company's research and development activities. The Company records its internal and third-party development costs associated with these collaborations as research and development expenses. When the Company is entitled to reimbursement of all or a portion of the research and development expenses that it incurs under a collaboration, the Company records those reimbursable amounts as collaboration revenue proportionately as the Company recognizes its expenses. If the collaboration is a cost-sharing arrangement in which both the Company and its collaborator perform development work and share costs, the Company also recognizes, as research and development expense in the period when its collaborator incurs development expenses, the portion of the collaborator's development expenses that the Company is obligated to reimburse. The Company may also be obligated to use commercially reasonable efforts to supply commercial bulk product to its collaborators. In such cases, the Company is reimbursed for its manufacturing costs as commercial product is shipped to its collaborators; however, recognition of such cost reimbursements as collaboration revenue is deferred until the product is sold by the Company's collaborators to third-party customers, at which time the Company's risk of inventory loss no longer exists. In addition, at that time, the related manufacturing costs for the sold product, which had been capitalized into inventory, are recognized by the Company. Under the Company's collaboration agreements, product sales and cost of sales for products which are currently approved are recorded by the Company's collaborators. The Company shares in any profits or losses arising from the commercialization of such products. The Company records its share of the profits or losses from commercialization of such products, representing net product sales less cost of goods sold and shared commercialization and other expenses, as collaboration revenue.
Research and Development Expenses	Research and Development Expenses Research and development expenses include costs directly attributable to the conduct of research and development programs, including the cost of salaries, payroll taxes, employee benefits, materials, supplies, depreciation on and maintenance of research equipment, costs related to research collaboration and licensing agreements, the cost of services provided by outside contractors, including services related to the Company's clinical trials, clinical trial expenses, the full cost of manufacturing drug for use in research, preclinical development, and clinical trials, amounts that the Company is obligated to reimburse to collaborators for research and development expenses that they incur, and the allocable portions of facility costs, such as rent, utilities, insurance, repairs and maintenance, depreciation, and general support services. Costs associated with research and development are expensed. Clinical trial costs are a significant component of research and development expenses and include costs associated with third-party contractors. The Company outsources a substantial portion of its clinical trial activities, utilizing external entities such as contract research organizations ("CROs"), independent clinical investigators, and other third-party service providers to assist the Company with the execution of its clinical studies. For each clinical trial that the Company conducts, certain clinical trial costs are expensed immediately, while others are expensed over time based on the expected total number of patients in the trial, the rate at which patients enter the trial, and/or the period over which clinical investigators or CROs are expected to provide services. Clinical activities which relate principally to clinical sites and other administrative functions to manage the Company's clinical trials are performed primarily by CROs. CROs typically perform most of the start-up activities for the Company's trials, including document preparation, site identification, screening and preparation, pre-study visits, training, and program management. These start-up costs usually occur within a few months after the contract has been executed and are event driven in nature. The remaining activities and related costs, such as patient monitoring and administration, generally occur ratably throughout the life of the individual contract or study. In the event of early termination of a clinical trial, the Company accrues and recognizes expenses in an amount based on its estimate of the remaining non-cancelable obligations associated with the winding down of the clinical trial and/or penalties. For clinical study sites, where payments are made periodically on a per-patient basis to the institutions performing the clinical study, the Company accrues expenses on an estimated cost-per-patient basis, based on subject enrollment and activity in each quarter. The amount of clinical study expense recognized in a quarter may vary from period to period based on the duration and progress of the study, the activities to be performed by the sites each quarter, the required level of patient enrollment, the rate at which patients actually enroll in and drop-out of the clinical study, and the number of sites involved in the study. Clinical trials that bear the greatest risk of change in estimates are typically those that have a significant number of sites, require a large number of patients, have complex patient screening requirements, and span multiple years. During the course of a trial, the Company adjusts its rate of clinical expense recognition if actual results differ from the Company's estimates. The Company's estimates and assumptions for clinical expense recognition could differ significantly from its actual results, which could cause material increases or decreases in research and development expenses in future periods when the actual results become known.
Stock-based Compensation	Stock-based Compensation The Company recognizes stock-based compensation expense for grants of stock option awards and restricted stock under the Company's Long-Term Incentive Plans to employees and non-employee members of the Company's board of directors based on the grant-date fair value of those awards. The grant-date fair value of an award is generally recognized as compensation expense over the award's requisite service period. The Company uses the Black-Scholes model to compute the estimated fair value of stock option awards. Using this model, fair value is calculated based on assumptions with respect to (i) expected volatility of the Company's Common Stock price, (ii) the periods of time over which employees and members of the board of directors are expected to hold their options prior to exercise (expected lives), (iii) expected dividend yield on the Common Stock, and (iv) risk-free interest rates. Stock-based compensation expense also includes an estimate, which is made at the time of grant, of the number of awards that are expected to be forfeited. This estimate is revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.
Income Taxes	Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined on the basis of the difference between the tax basis of assets and liabilities and their respective financial reporting amounts ("temporary differences") at enacted tax rates in effect for the years in which the differences are expected to reverse. A valuation allowance is established for deferred tax assets for which it is more likely than not that some portion or all of the deferred tax assets will not be realized. Uncertain tax positions, for which management's assessment is that there is more than a 50% probability of sustaining the position upon challenge by a taxing authority based upon its technical merits, are subjected to certain recognition and measurement criteria. The Company re-evaluates uncertain tax positions and consider various factors, including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, and changes in facts or circumstances related to a tax position. The Company adjusts the level of the liability to reflect any subsequent changes in the relevant facts and circumstances surrounding the uncertain positions. The Company recognizes interest and penalties related to income tax matters in income tax expense.
Per Share Data	Per Share Data Basic net income per share is computed by dividing net income by the weighted average number of shares of Common Stock and Class A Stock outstanding. Net income per share is presented on a combined basis, inclusive of Common Stock and Class A Stock outstanding, as each class of stock has equivalent economic rights. Basic net income per share excludes restricted stock awards until vested. Diluted net income per share includes the potential dilutive effect of common stock equivalents as if such securities were converted or exercised during the period, when the effect is dilutive. Common stock equivalents include: (i) outstanding stock options and restricted stock awards under the Company's Long-Term Incentive Plans, which are included under the "treasury stock method" when dilutive, (ii) Common Stock to be issued upon the assumed conversion of the Company's convertible senior notes, which are included under the "if-converted method" when dilutive, and (iii) Common Stock to be issued upon the exercise of outstanding warrants, which are included under the "treasury stock method" when dilutive.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments which potentially expose the Company to concentrations of credit risk consist of cash, cash equivalents, certain financial instruments, and accounts receivable. A large portion of the Company's cash is held by a few major financial institutions. In accordance with the Company's policies, the Company mandates asset diversification and monitors exposure with its counterparties. Concentrations of credit risk with respect to accounts receivable are significant. Accounts receivable from product sales of EYLEA and ARCALYST are due from several distributors and specialty pharmacies, who are the Company's customers. As of December 31, 2016 , three individual customers accounted for 99% of the Company's net trade accounts receivable balances. As of December 31, 2015, two individual customers accounted for 94% of the Company's net trade accounts receivable balances.The Company has contractual payment terms with each of its customers, and the Company monitors its customers' financial performance and credit worthiness so that it can properly assess and respond to any changes in their credit profile. In addition, the Company may insure a portion of its accounts receivables within its overall risk management practices. As of December 31, 2016 and 2015, there were no reserves against trade accounts receivable. In addition, during the years ended December 31, 2016, 2015, and 2014, the Company did no t recognize any charges for write-offs of trade accounts receivable.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In May 2014, the FASB issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers , which will replace existing revenue recognition guidance. The new standard requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. To achieve that core principle, an entity must identify the contract(s) with a customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue when (or as) the entity satisfies the performance obligation. In July 2015, the FASB decided to delay the effective date of the new standard by one year; as a result, the new standard will be effective for annual and interim reporting periods beginning after December 15, 2017. Early adoption will be permitted, but no earlier than 2017 for calendar year-end entities. The standard allows for two transition methods - retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying the standard recognized at the date of initial adoption. The Company has not yet determined its method of transition. The Company does not expect the new standard to have a material impact on the recognition of revenue from product sales. However, the Company continues to evaluate the impact that this guidance will have on its financial statements in connection with collaboration and license agreements. In January 2016, the FASB issued Accounting Standards Update 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities . The amendments require equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. The amendments are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. The implementation of the amendments is expected to increase the volatility of an entity's net income; however, the Company is not currently able to estimate the impact of adopting these amendments, as the significance of the impact will depend on the Company's equity investment balance upon adoption. In February 2016, the FASB issued Accounting Standards Update 2016-02, Leases . The new standard requires a lessee to recognize in its balance sheet (for both finance and operating leases) a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term. The amendments are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The Company is evaluating the impact that this guidance will have on the Company's financial statements. In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update 2016-09 ("ASU 2016-09"), Compensation - Stock Compensation, Improvements to Employee Share-Based Payment Accounting , which the Company elected to early adopt during the second quarter of 2016. ASU 2016-09 requires an entity to recognize all excess tax benefits and tax deficiencies in connection with stock-based compensation as income tax expense or benefit in the income statement (previously, excess tax benefits were recognized in additional paid-in capital). This aspect of ASU 2016-09 was adopted prospectively, and accordingly, the Company recorded excess tax benefits of $144.8 million within income tax expense for the year ended December 31, 2016. Included within income tax expense for the year ended December 31, 2016 is $15.6 million of excess tax benefits, which was previously recorded to additional paid-in capital during the first quarter of 2016. The amendments also require recognition of excess tax benefits regardless of whether the benefit reduces taxes payable in the current period. Furthermore, the amendments require that excess tax benefits be classified as an operating activity in the statement of cash flows (such amounts were previously included as a financing activity in the statement of cash flows); the Company also adopted this provision of ASU 2016-09 prospectively.
Legal Costs	Costs associated with the Company's involvement in legal proceedings are expensed as incurred.
Fair Value Transfer	The Company's policy for recognition of transfers between levels of the fair value hierarchy is to recognize any transfer at the beginning of the fiscal quarter in which the determination to transfer was made.

Business Overview and Summary28

Business Overview and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Estimated useful lives of property, plant, and equipment [Table Text Block]	The estimated useful lives of property, plant, and equipment are as follows: Building and improvements 10-40 years Laboratory and other equipment 3-10 years Furniture and fixtures 5 years

Net Product Sales (Tables)

Net Product Sales (Tables)	12 Months Ended
	Dec. 31, 2016
Revenues [Abstract]
Schedules of Concentration of Risk, by Risk Factor	The Company's product sales to certain customers that accounted for more than 10% of total gross product revenue for each of the years ended December 31, 2016, 2015, and 2014. Sales to each of these customers as a percentage of the Company's total gross product revenue are as follows: Year Ended December 31, 2016 2015 2014 Besse Medical, a subsidiary of AmerisourceBergen Corporation 55 % 67 % 73 % McKesson Corporation 28 % 26 % 20 % Curascript SD Specialty Distribution, a subsidiary of Express Scripts 16 % ** ** ** For the periods ending December 31, 2015 and 2014, sales to Curascript SD Specialty Distribution represented less than 10% of total gross product revenue.
Sales Related Deductions Activity	The following table summarizes the provisions, and credits/payments, for these sales-related deductions for the years ended December 31, 2016, 2015, and 2014. Rebates & Chargebacks Distribution- Related Fees Other Sales- Related Deductions Total Balance as of December 31, 2013 $ 4,400 $ 19,663 $ 538 $ 24,601 Provision related to current period sales 33,117 77,160 1,578 111,855 Credits/payments (34,434 ) (75,657 ) (1,584 ) (111,675 ) Balance as of December 31, 2014 3,083 21,166 532 24,781 Provision related to current period sales 61,124 122,466 9,600 193,190 Credits/payments (57,788 ) (95,319 ) (9,615 ) (162,722 ) Balance as of December 31, 2015 6,419 48,313 517 55,249 Provision related to current period sales 93,385 154,477 30,442 278,304 Credits/payments (87,092 ) (173,325 ) (27,285 ) (287,702 ) Balance as of December 31, 2016 $ 12,712 $ 29,465 $ 3,674 $ 45,851

Collaboration Agreements (Table

Collaboration Agreements (Tables)	12 Months Ended
	Dec. 31, 2016
Collaboration Agreement [Abstract]
Schedule of Related Party Transactions	The collaboration revenue the Company earned from Sanofi is detailed below: Year Ended December 31, Sanofi Collaboration Revenue 2016 2015 2014 Antibody: Reimbursement of Regeneron research and development expenses $ 564,900 $ 735,439 $ 547,761 Reimbursement of Regeneron commercialization-related expenses 322,149 157,350 19,480 Regeneron's share of losses in connection with commercialization of antibodies (459,058 ) (240,042 ) (41,378 ) Other 12,177 10,243 10,243 Total Antibody 440,168 662,990 536,106 Immuno-oncology: Reimbursement of Regeneron research and development expenses 138,497 39,961 — Other 80,000 40,000 — Total Immuno-oncology 218,497 79,961 — ZALTRAP: Regeneron's share of losses in connection with commercialization of ZALTRAP — — (4,715 ) Reimbursement of Regeneron research and development expenses — 686 4,806 Other — 15,236 5,102 Total ZALTRAP — 15,922 5,193 $ 658,665 $ 758,873 $ 541,299
Schedule of Selected Financial Information - Sanofi	Other selected financial information in connection with the Company's collaboration agreements with Sanofi is as follows: As of December 31, 2016 2015 Antibody: Accounts receivable, net $ 47,268 $ 126,687 Deferred revenue 98,741 84,237 Immuno-oncology: Accounts receivable, net $ 40,647 $ 21,394 Deferred revenue 520,000 600,000
Collaboration revenue	The collaboration revenue the Company earned from Bayer is detailed below: Year Ended December 31, Bayer Collaboration Revenue 2016 2015 2014 EYLEA: Regeneron's net profit in connection with commercialization of EYLEA outside the United States $ 649,232 $ 466,667 $ 301,302 Sales milestones — 15,000 105,000 Cost-sharing of Regeneron EYLEA development expenses 9,010 8,887 23,383 Other 52,527 69,466 52,390 Total EYLEA 710,769 560,020 482,075 PDGFR-beta antibody: Cost-sharing of rinucumab/aflibercept (REGN2176-3) development expenses 10,291 10,075 2,848 Other 9,576 10,393 10,632 Total PDGFR-beta antibody 19,867 20,468 13,480 Ang2 antibody: Cost-sharing of nesvacumab/aflibercept (REGN910-3) development expenses 8,036 — — Other 5,598 — — Total Ang2 antibody 13,634 — — $ 744,270 $ 580,488 $ 495,555
Schedule of Selected Financial Information - Bayer	Deferred revenue in connection with the Company's collaboration agreements with Bayer is as follows: As of December 31, 2016 2015 EYLEA $ 62,373 $ 46,694 PDGFR-beta antibody — 9,522 Ang2 antibody 45,739 —

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities	The following tables summarize the Company's investments in marketable securities: Amortized Unrealized Fair As of December 31, 2016 Cost Basis Gains Losses Value Corporate bonds $ 1,076,964 $ 630 $ (4,743 ) $ 1,072,851 U.S. government and government agency obligations 132,923 58 (641 ) 132,340 Municipal bonds 7,663 1 (20 ) 7,644 Commercial paper 63,074 1 — 63,075 Certificates of deposit 42,612 — — 42,612 Equity securities 57,251 5,551 (13,583 ) 49,219 $ 1,380,487 $ 6,241 $ (18,987 ) $ 1,367,741 As of December 31, 2015 Corporate bonds $ 770,092 $ 156 $ (2,565 ) $ 767,683 U.S. government and government agency obligations 51,402 — (193 ) 51,209 Municipal bonds 17,930 5 (11 ) 17,924 Equity securities 17,005 14,462 — 31,467 $ 856,429 $ 14,623 $ (2,769 ) $ 868,283
Marketable Securities, Based on Contractual Maturity Dates	The fair values of debt security investments by contractual maturity consist of the following: As of December 31, 2016 2015 Maturities within one year $ 503,482 $ 236,121 Maturities after one year through five years 815,040 600,695 $ 1,318,522 $ 836,816
Fair Value and Unrealized Losses of Marketable Securities	The following table shows the fair value of the Company's marketable securities that have unrealized losses and that are deemed to be only temporarily impaired, aggregated by investment category and length of time that the individual securities have been in a continuous unrealized loss position. Less than 12 Months 12 Months or Greater Total As of December 31, 2016 Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss Corporate bonds $ 759,222 $ (4,685 ) $ 36,407 $ (58 ) $ 795,629 $ (4,743 ) U.S. government and government agency obligations 81,170 (641 ) — — 81,170 (641 ) Municipal bonds 7,141 (20 ) — — 7,141 (20 ) Equity securities 36,417 (13,583 ) — — 36,417 (13,583 ) $ 883,950 $ (18,929 ) $ 36,407 $ (58 ) $ 920,357 $ (18,987 ) As of December 31, 2015 Corporate bonds $ 668,199 $ (2,473 ) $ 23,749 $ (92 ) $ 691,948 $ (2,565 ) U.S. government and government agency obligations 51,215 (193 ) — — 51,215 (193 ) Municipal bonds 11,917 (11 ) — — 11,917 (11 ) $ 731,331 $ (2,677 ) $ 23,749 $ (92 ) $ 755,080 $ (2,769 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Schedule of assets measured at fair value on a recurring basis	The Company's assets that are measured at fair value on a recurring basis consist of the following: Fair Value Measurements at Reporting Date Using As of December 31, 2016 Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Available-for-sale marketable securities: Corporate bonds $ 1,072,851 — $ 1,072,851 U.S. government and government agency obligations 132,340 — 132,340 Municipal bonds 7,644 — 7,644 Commercial paper 63,075 — 63,075 Certificates of deposit 42,612 — 42,612 Equity securities 49,219 $ 49,219 — $ 1,367,741 $ 49,219 $ 1,318,522 As of December 31, 2015 Available-for-sale marketable securities: Corporate bonds $ 767,683 — $ 767,683 U.S. government and government agency obligations 51,209 — 51,209 Municipal bonds 17,924 — 17,924 Equity securities 31,467 $ 31,467 — $ 868,283 $ 31,467 $ 836,816

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2016
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	Inventories consist of the following: As of December 31, 2016 2015 Raw materials $ 92,287 $ 59,151 Work-in-process 202,301 132,068 Finished goods 13,334 11,197 Deferred costs 91,434 36,162 $ 399,356 $ 238,578

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant, and equipment consist of the following: As of December 31, 2016 2015 Land $ 103,906 $ 77,826 Building and improvements 1,278,283 760,517 Leasehold improvements 101,101 95,226 Construction-in-progress 318,929 579,834 Laboratory and other equipment 554,181 330,432 Furniture, computer and office equipment, and other 152,525 81,381 2,508,925 1,925,216 Less, accumulated depreciation and amortization (425,504 ) (331,096 ) $ 2,083,421 $ 1,594,120

Accounts Payable and Accrued 35

Accounts Payable and Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2016
Payables and Accruals [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and accrued expenses consist of the following: As of December 31, 2016 2015 Accounts payable $ 134,984 $ 140,962 Accrued payroll and related costs 153,086 133,223 Accrued clinical trial expense 91,753 88,297 Accrued sales-related charges, deductions, and royalties 159,985 195,986 Income taxes payable 235,776 — Other accrued expenses and liabilities 103,512 85,644 $ 879,096 $ 644,112

Deferred Revenue (Tables)

Deferred Revenue (Tables)	12 Months Ended
	Dec. 31, 2016
Deferred Revenue Disclosure [Abstract]
Deferred Revenue, by Arrangement, Disclosure	Deferred revenue consists of the following: As of December 31, 2016 2015 Current portion: Received or receivable from Sanofi (see Note 3a) $ 115,267 $ 101,573 Received or receivable from Bayer (see Note 3b) 31,084 24,290 Received or receivable from MTPC (see Note 3c) 9,188 2,352 Received or receivable from Teva (see Note 3d) 43,122 — Received for technology license agreement (see Note 4) 23,572 23,572 Other 9,431 1,700 $ 231,664 $ 153,487 Long-term portion: Received or receivable from Sanofi (see Note 3a) $ 503,474 $ 582,664 Received or receivable from Bayer (see Note 3b) 77,028 31,926 Received or receivable from MTPC (see Note 3c) 45,940 7,059 Received or receivable from Teva (see Note 3d) 194,050 — Received for technology license agreement (see Note 4) 10,280 33,851 Other — 9,179 $ 830,772 $ 664,679

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Instrument [Line Items]
Schedule of Long-term Debt Instruments	The net carrying amount of the liability component of the Notes consists of the following: As of December 31, 2016 2015 Total convertible senior notes - par $ — $ 11,154 Unamortized discount — (352 ) $ — $ 10,802
Interest Expense Associated with Convertible Notes	Total interest expense associated with the Notes, net of capitalized interest as applicable, consists of the following: Year Ended December 31, 2016 2015 2014 Contractual coupon interest rate $ 7 $ 544 $ 5,036 Amortization of discount and note issuance costs 150 2,818 17,821 $ 157 $ 3,362 $ 22,857

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Other Commitments [Line Items]
Commitments under facility lease obligation [Table Text Block]	The estimated future minimum noncancelable commitments under these facility lease obligations, as of December 31, 2016, exclusive of the potential impact of the closing of the Purchase Agreement (which is anticipated to occur in the first quarter of 2017), are as follows: Buildings A and B Building C Buildings D and E Building F Total 2017 $ 13,965 $ 4,740 $ 12,922 $ 490 $ 32,117 2018 14,242 4,873 13,267 759 33,141 2019 14,526 5,009 13,621 786 33,942 2020 14,818 5,149 13,983 813 34,763 2021 15,116 5,292 14,354 841 35,603 Thereafter 101,010 48,801 121,927 7,190 278,928 $ 173,677 $ 73,864 $ 190,074 $ 10,879 $ 448,494
Commitments Under Operating Leases	The estimated future minimum noncancelable lease commitments under operating leases, as of December 31, 2016, are as follows: Facilities Equipment Total 2017 $ 4,728 $ 5,156 $ 9,884 2018 4,860 825 5,685 2019 4,817 273 5,090 2020 4,271 12 4,283 2021 3,982 11 3,993 Thereafter 22,336 — 22,336 $ 44,994 $ 6,277 $ 51,271
Rent Expense Under Operating Leases	Rent expense under operating leases was: Year Ended December 31, Facilities Equipment Total 2016 $ 15,861 $ 852 $ 16,713 2015 14,659 543 15,202 2014 13,360 952 14,312
Facility lease obligation [Table Text Block]	Facility lease obligations consist of the following: As of December 31, 2016 2015 Buildings A and B $ 99,323 $ 108,857 Building C 44,338 49,475 Buildings D and E 194,037 206,376 Building F 16,154 — $ 353,852 $ 364,708

Long-Term Incentive Plans (Tabl

Long-Term Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Transactions Involving Stock Option Awards	Transactions involving stock option awards during 2016 under the Company's Incentive Plans are summarized in the table below. Stock Options: Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Intrinsic Value Outstanding as of December 31, 2015 23,165,769 $ 236.75 2016: Granted 4,201,978 $ 386.44 Forfeited (468,798 ) $ 398.57 Expired (20,645 ) $ 420.04 Exercised (1,742,277 ) $ 76.79 Outstanding as of December 31, 2016 25,136,027 $ 269.69 6.66 $ 3,399,815 Vested and expected to vest as of December 31, 2016 24,598,430 $ 266.16 6.60 $ 3,397,437 Exercisable as of December 31, 2016 15,140,287 $ 166.96 5.19 $ 3,299,296
Weighted-Average Exercise Prices and Weighted-Average Grant-Date Fair Values of Options Issued	The fair value of each option granted under the Company's Incentive Plans during these periods was estimated on the date of grant using the Black-Scholes option-pricing model. Number of Options Granted Weighted-Average Exercise Price Weighted-Average Fair Value 2016: Exercise price equal to Market Price 4,201,978 $ 386.44 $ 126.68 2015: Exercise price equal to Market Price 4,495,487 $ 537.29 $ 181.65 2014: Exercise price equal to Market Price 3,913,368 $ 385.33 $ 140.38
Weighted-Average Values of Assumptions Used in Computing Fair Value of Option Grants	The following table summarizes the weighted average values of the assumptions used in computing the fair value of option grants during 2016, 2015, and 2014. 2016 2015 2014 Expected volatility 34 % 35 % 39 % Expected lives from grant date 5.1 years 5.1 years 5.2 years Expected dividend yield 0 % 0 % 0 % Risk-free interest rate 1.84 % 1.68 % 1.62 %
Activity Related to Restricted Stock Awards	A summary of the Company's activity related to Restricted Stock awards during 2016 is summarized below: Restricted Stock: Number of Shares Weighted-Average Grant Date Fair Value Outstanding as of December 31, 2015 541,700 $ 133.96 2016: Granted 16,750 $ 385.84 Vested (11,590 ) $ 125.38 Forfeited (40 ) $ 237.68 Outstanding as of December 31, 2016 546,820 $ 141.85
Schedule of Error Corrections and Prior Period Adjustments		.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]	Components of income before income taxes consist of the following: Year Ended December 31, 2016 2015 2014 United States $ 1,650,959 $ 1,665,087 $ 1,101,446 Foreign (321,144 ) (439,990 ) (340,211 ) $ 1,329,815 $ 1,225,097 $ 761,235
Schedule of Components of Income Tax Expense (Benefit)	Components of income tax expense consist of the following: Year Ended December 31, 2016 2015 2014 Current: Federal $ 786,964 $ 686,561 $ 437,038 State 8,769 28,568 28,718 Foreign (1,362 ) 4,004 2,879 Total current tax expense 794,371 719,133 468,635 Deferred: Federal (377,368 ) (119,849 ) (62,932 ) State 13,431 (3,768 ) 18,891 Foreign 3,859 (6,475 ) (1,485 ) Total deferred tax (benefit) expense (360,078 ) (130,092 ) (45,526 ) $ 434,293 $ 589,041 $ 423,109
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the U.S. statutory income tax rate to the Company's effective income tax rate is as follows: Year Ended December 31, 2016 2015 2014 U.S. federal statutory tax rate 35.0 % 35.0 % 35.0 % Stock-based compensation (10.9 ) — — State and local income taxes 0.3 1.0 2.4 Change in state effective rate 1.0 (0.1 ) 2.9 Foreign income tax rate differential 8.8 12.2 15.8 Income tax credits (1.2 ) (1.6 ) (5.1 ) Non-deductible Branded Prescription Drug Fee 1.9 2.0 2.8 Domestic production activities deduction (2.8 ) (3.2 ) — Other permanent differences 0.6 2.8 1.8 Effective income tax rate 32.7 % 48.1 % 55.6 %
Schedule of Deferred Tax Assets and Liabilities	Significant components of the Company's deferred tax assets and liabilities are as follows: As of December 31, 2016 2015 Deferred tax assets: Net operating loss carryforward $ 137 $ 140 Fixed and intangible assets 21,139 — Deferred revenue 214,587 51,766 Deferred compensation 515,984 349,508 Capitalized research and development costs 2,492 7,725 Accrued expenses 37,188 47,520 Other 46,471 26,580 837,998 483,239 Valuation allowance (3,420 ) — Total deferred tax assets 834,578 483,239 Deferred tax liabilities: Unrealized gains/losses on marketable securities — (3,280 ) Fixed assets and intangible assets — (5,559 ) Other (9,275 ) (12,455 ) Total deferred tax liabilities (9,275 ) (21,294 ) Net deferred tax assets $ 825,303 $ 461,945
Schedule Of Unrecognized Tax Benefits Roll Forward	The following table summarizes the gross amounts of unrecognized tax benefits. The amount of unrecognized tax benefits that, if settled, would impact the effective tax rate is $107.2 million , $102.1 million , and $51.2 million as of December 31, 2016, 2015, and 2014, respectively. 2016 2015 2014 Balance as of January 1 $ 116,572 $ 57,615 $ 26,627 Gross increases related to current year tax positions 45,575 59,909 27,538 Gross (decreases) increases related to prior year tax positions (42,284 ) (952 ) 6,464 Gross decrease due to settlements, recapture, filed returns, and lapse of statutes of limitation (2,697 ) — (3,014 ) Balance as of December 31 $ 117,166 $ 116,572 $ 57,615

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Basic and Diluted Net Income (Loss) Per Share	The calculations of basic and diluted net income per share are as follows: Year Ended December 31, 2016 2015 2014 Net income - basic $ 895,522 $ 636,056 $ 338,126 Effect of dilutive securities: Convertible senior notes - interest expense related to contractual coupon interest rate and amortization of discount and note issuance costs 397 — — Net income - diluted $ 895,919 $ 636,056 $ 338,126 (Shares in thousands) Weighted average shares - basic 104,719 103,061 100,612 Effect of dilutive securities: Stock options 10,177 9,446 9,440 Restricted stock 474 477 425 Convertible senior notes 61 — — Warrants 936 2,246 2,936 Dilutive potential shares 11,648 12,169 12,801 Weighted average shares - diluted 116,367 115,230 113,413 Net income per share - basic $ 8.55 $ 6.17 $ 3.36 Net income per share - diluted $ 7.70 $ 5.52 $ 2.98
Antidilutive Securities	Shares which have been excluded from diluted per share amounts because their effect would have been antidilutive, include the following: Year Ended December 31, (Shares in thousands) 2016 2015 2014 Stock options 8,041 1,343 1,470 Restricted stock 19 — — Convertible senior notes — 994 4,247

Unaudited Quarterly Results (Ta

Unaudited Quarterly Results (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Summarized quarterly financial data for the years ended December 31, 2016 and 2015 are set forth in the following tables. First Quarter Ended March 31, 2016 * Second Quarter Ended June 30, 2016 Third Quarter Ended September 30, 2016 Fourth Quarter Ended December 31, 2016 (Unaudited) Revenues $ 1,200,849 $ 1,212,629 $ 1,220,122 $ 1,226,827 Net income $ 181,385 $ 196,218 $ 264,804 $ 253,115 Net income per share - basic $ 1.74 $ 1.88 $ 2.53 $ 2.41 Net income per share - diluted $ 1.59 $ 1.69 $ 2.27 $ 2.19 First Quarter Ended March 31, 2015 Second Quarter Ended June 30, 2015 Third Quarter Ended September 30, 2015 Fourth Quarter Ended December 31, 2015 (Unaudited) Revenues $ 869,612 $ 998,617 $ 1,137,422 $ 1,098,077 Net income $ 76,021 $ 194,643 $ 210,398 $ 154,994 Net income per share - basic $ 0.74 $ 1.89 $ 2.04 $ 1.49 Net income per share - diluted $ 0.66 $ 1.69 $ 1.82 $ 1.34 * Due to the adoption of ASU 2016-09, the Company revised its net income from the amounts originally reported for the quarterly period ended March 31, 2016 to include a $15.6 million income tax benefit, which was originally recorded as additional paid-in capital.

Business Overview and Summary43

Business Overview and Summary of Significant Accounting Policies (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Excess tax benefit from stock-based compensation		$ 0	$ 405,317,000	$ 439,278,000
Revenue Recognition [Abstract]
Percentage of prompt pay discount the company accrues		100.00%
Concentration Risks, Types, No Concentration Percentage [Abstract]
Allowance for Doubtful Accounts Receivable, Current		$ 0	0
Provision for Doubtful Accounts		$ 0	$ 0	$ 0
Building and improvements | Minimum
Estimated useful life		10 years
Building and improvements | Maximum
Estimated useful life		40 years
Laboratory and other equipment | Minimum
Estimated useful life		3 years
Laboratory and other equipment | Maximum
Estimated useful life		10 years
Furniture and Fixtures [Member] | Maximum
Estimated useful life		5 years
Accounting Standards Update 2016-09 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Excess tax benefit from stock-based compensation		$ 144,800,000
Gross Sales Revenue | Customer concentration risk
Concentration risk, percentage		99.00%	94.00%
Additional Paid-in Capital | Accounting Standards Update 2016-09 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Excess tax benefit from stock-based compensation	$ 15,600,000

Net Product Sales (Details)

Net Product Sales (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue Disclosure [Line Items]
Net product sales	$ 3,338,390	$ 2,689,478	$ 1,750,762
Activity of Sales Related Deductions [Roll Forward]
Balance	45,851	55,249	24,781	$ 24,601
Provision related to current period sales	278,304	193,190	111,855
Credits/payments	(287,702)	(162,722)	(111,675)
Rebates and Chargebacks
Activity of Sales Related Deductions [Roll Forward]
Balance	12,712	6,419	3,083	4,400
Provision related to current period sales	93,385	61,124	33,117
Credits/payments	(87,092)	(57,788)	(34,434)
Distribution Related Fees
Activity of Sales Related Deductions [Roll Forward]
Balance	29,465	48,313	21,166	19,663
Provision related to current period sales	154,477	122,466	77,160
Credits/payments	(173,325)	(95,319)	(75,657)
Other Sales Related Deductions
Activity of Sales Related Deductions [Roll Forward]
Balance	3,674	517	532	$ 538
Provision related to current period sales	30,442	9,600	1,578
Credits/payments	$ (27,285)	$ (9,615)	(1,584)
Customer concentration risk | Gross Sales Revenue
Risks and Uncertainties [Abstract]
Concentration risk, percentage	99.00%	94.00%
EYLEA
Revenue Disclosure [Line Items]
Net product sales	$ 3,323,100	$ 2,676,000	1,736,400
ARCALYST
Revenue Disclosure [Line Items]
Net product sales	$ 15,300	$ 13,500	$ 14,400
Besse Medical | Customer concentration risk | Gross Sales Revenue
Risks and Uncertainties [Abstract]
Concentration risk, percentage	55.00%	67.00%	73.00%
McKesson Corporation | Customer concentration risk | Gross Sales Revenue
Risks and Uncertainties [Abstract]
Concentration risk, percentage	28.00%	26.00%	20.00%
Curascript SD | Customer concentration risk | Gross Sales Revenue
Risks and Uncertainties [Abstract]
Concentration risk, percentage	16.00%
Curascript SD | Maximum | Customer concentration risk | Gross Sales Revenue
Risks and Uncertainties [Abstract]
Concentration risk, percentage		10.00%	10.00%

Collaboration Agreements (Sanof

Collaboration Agreements (Sanofi) (Details) $ in Thousands	1 Months Ended					3 Months Ended	12 Months Ended
	Jul. 30, 2016	Jul. 31, 2015USD ($)	Jul. 31, 2014USD ($)	Nov. 30, 2009USD ($)	Nov. 30, 2007USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013
Collaboration Agreements [Line Items]
Accounts receivable - trade, net								$ 1,343,368	$ 1,152,489
Deferred revenue from Sanofi, current portion								115,267	101,573
Research and Development Expense								2,052,295	1,620,577	$ 1,271,353
Revenue from Related Parties								658,665	758,873	$ 541,299
Period for Achieving Sales Target for Milestone Payment, Rolling Basis										12 months
Other Revenue, Net								119,102	74,889	$ 31,941
Payments to Acquire Marketable Securities								809,419	557,105	564,188
Period over which we have obligation	5 years
PDGFR-beta outside the US
Collaboration Agreements [Line Items]
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned								10,291	10,075	2,848
Contracts Revenue								$ 9,576	10,393	10,632
Percentage of development cost for the territory outside the United States to be paid for under the collaboration								50.00%
Deferred Revenue, Additions										2,500
Percentage of global development cost to be paid by the collaboration partner under the collaboration								25.00%
Proceeds from Collaborators										25,500
Substantive milestone payment to the Company									5,000
Collaboration Agreement with Sanofi
Collaboration Agreements [Line Items]
Common Stock, shares issued (in shares) | shares								23,418,396
IO Agreement [Member]
Collaboration Agreements [Line Items]
Deferred Revenue, Additions								$ 640,000
Antibody Collaboration
Collaboration Agreements [Line Items]
Accounts receivable - trade, net								47,268	126,687
Deferred revenue from Sanofi, current portion								98,741	84,237
Contingent reimbursement obligation								2,245,000
Recognition of Deferred Revenue								12,177	10,243	10,243
Net profit (loss) from commercialization of products under collaboration agreement								(459,058)	(240,042)	(41,378)
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned								564,900	735,439	547,761
Contracts Revenue								322,149	157,350	19,480
License agreement term		3 years
Research and Development Expense								108,600	92,600	109,700
Revenue from Related Parties								$ 440,168	662,990	536,106
Proceeds from Collaborators					$ 85,000
Percentage of repayment of development balance out of profits								50.00%
Minimum advance notice required to terminate collaboration agreement								3 months
Annual funding maximum of research activities per amended agreement				$ 160,000				$ 130,000	145,000
Reduction of Funding for Research Activities Per Agreement		$ 75,000
Substantive milestone payment to the Company									10,000
Percentage of Trial Costs borne by collaborating party								80.00%
Percentage of Trial Costs borne by entity								20.00%
Percentage of trial costs to be reimbursed due to profitability of agreement								30.00%
Excess Share of profit not required to to be applied to reimburse development cost								10.00%
Starting share of profits outside the United States, based on sales, for collaborating party								65.00%
Starting share of profits outside the United States, based on sales, for Company								35.00%
Ending share of profits outside the United States, based on sales, for collaborating party								55.00%
Ending share of profits outside the United States, based on sales, for Company								45.00%
Share of losses outside the United States, for collaborating party								55.00%
Share of losses outside the United States, for Company								45.00%
Maximum amount of sales milestone payments if total sales achieve specific levels								$ 250,000
Starting specified levels of annual sales at which sales milestone payments may be received								$ 1,000,000
Period for Achieving Sales Target for Milestone Payment, Rolling Basis								12 months
Amount of funding of agreed-upon cost incurred to expand manufacturing capacity				$ 30,000
Maximum amount of reimbursement related to capital expenditures										17,500
Period of Notice to Opt Out of Further Development and or Commercialization								12 months
Period of Notice to Opt Out of Further Development Upon Entering of Joint Development Product								30 days
Number of families of novel antibodies											2
Payments for Purchase of Other Assets			$ 67,500
Immuno-oncology Agreement [Member]
Collaboration Agreements [Line Items]
Accounts receivable - trade, net								$ 40,647	21,394
Deferred revenue from Sanofi, current portion								520,000	600,000
Contingent reimbursement obligation								3,000
Recognition of Deferred Revenue								80,000	40,000	0
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned								138,497	39,961	0
Revenue from Related Parties								218,497	79,961	$ 0
Sanofi
Collaboration Agreements [Line Items]
Research and Development Asset Acquired Other than Through Business Combination, Written-off			$ (33,800)
VelociGene Agreement
Collaboration Agreements [Line Items]
Minimum payment received under the agreement								21,500
PDGF
Collaboration Agreements [Line Items]
Number of Payments the Company made										2
Other Research and Development Expense									10,000	$ 5,000
ZALTRAP Agreement
Collaboration Agreements [Line Items]
Net profit (loss) from commercialization of products under collaboration agreement								0	0	(4,715)
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned								0	686	4,806
Contracts Revenue								0	15,236	5,102
Deferred Revenue, Revenue Recognized						$ 14,900
Revenue from Related Parties								0	15,922	$ 5,193
Other Revenue, Net								26,200	$ 38,800
IO Discovery Agreement [Member]
Collaboration Agreements [Line Items]
License agreement term		5 years
Deferred Revenue, Additions		$ 265,000
Potential future R&D expenses		1,090,000
Funding Maximum of Research Activities Per Agreement		$ 825,000
Annual Funding Limit - 2016								$ 150,000
Additional years to extend the agreement		3 years
Excess Share of profit not required to to be applied to reimburse development cost		10.00%
IO License and Collaboration Agreement [Member]
Collaboration Agreements [Line Items]
Deferred Revenue, Additions		$ 375,000
Excess Share of profit not required to to be applied to reimburse development cost		10.00%
Period of Notice to Opt Out of Further Development and or Commercialization		12 months
New Funding [Member] | IO Discovery Agreement [Member]
Collaboration Agreements [Line Items]
Funding Maximum of Research Activities Per Agreement		$ 750,000
Previous Funding under Antibody Discovery Agreement [Member] | IO Discovery Agreement [Member]
Collaboration Agreements [Line Items]
Funding Maximum of Research Activities Per Agreement		75,000
PD-1 [Member] | IO License and Collaboration Agreement [Member]
Collaboration Agreements [Line Items]
Levels of twelve month sales at which sales milestone payments would be received		2,000,000
Maximum amount of shared development costs		650,000
Maximum amount of sales milestone payments if total sales achieve specific levels		$ 375,000
Period for Achieving Sales Target for Milestone Payment, Rolling Basis		12 months
Minimum | ZALTRAP Agreement
Collaboration Agreements [Line Items]
Percentage of aggregate net sales to be paid by the related party in such calendar year								15.00%
Maximum | ZALTRAP Agreement
Collaboration Agreements [Line Items]
Percentage of aggregate net sales to be paid by the related party in such calendar year								30.00%
Scenario, Forecast [Member] | Antibody Collaboration
Collaboration Agreements [Line Items]
Annual funding maximum of research activities per amended agreement							$ 130,000
Subsequent Event [Member] | Antibody Collaboration
Collaboration Agreements [Line Items]
License agreement term							3 years

Collaboration Agreements (Bayer

Collaboration Agreements (Bayer HealthCare LLC) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Aug. 31, 2007	Oct. 31, 2006	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Collaboration Agreements [Line Items]
Accounts receivable from Bayer HealthCare					$ 175,263	$ 162,152
Deferred revenue, current portion					231,664	153,487
Other Collaboration Revenue					744,270	580,488	$ 495,555
Collaboration Agreement with Bayer HealthCare LLC
Collaboration Agreement [Abstract]
Contingent reimbursement obligation					256,000
Collaboration Agreements [Line Items]
Deferred Revenue, Additions		$ 20,000	$ 75,000
Net profit (loss) from commercialization of products under collaboration agreement					649,232	466,667	301,302
Revenue Recognition, Milestone Method, Revenue Recognized					0	15,000	105,000
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned					9,010	8,887	23,383
Other Collaboration Revenue					710,769	560,020	482,075
Contracts Revenue					52,527	69,466	52,390
EYLEA
Collaboration Agreements [Line Items]
Deferred revenue, current portion					62,373	46,694
PDGFR-beta outside the US
Collaboration Agreements [Line Items]
Deferred Revenue, Additions							2,500
Deferred revenue, current portion					0	9,522
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned					10,291	10,075	2,848
Other Collaboration Revenue					19,867	20,468	13,480
Contracts Revenue					$ 9,576	10,393	10,632
Percentage of global development cost to be paid by the collaboration partner under the collaboration					25.00%
Percentage of development cost for the territory outside the United States to be paid for under the collaboration					50.00%
Ang2
Collaboration Agreements [Line Items]
Deferred revenue, current portion					$ 45,739	0
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned					8,036	0	0
Other Collaboration Revenue					13,634	0	0
Contracts Revenue					5,598	$ 0	$ 0
Ang2 Antibody [Member]
Collaboration Agreements [Line Items]
Deferred Revenue, Additions	$ 50,000
Percentage of global development cost to be paid by the collaboration partner under the collaboration	25.00%
Percentage of development cost for the territory outside the United States to be paid for under the collaboration	50.00%
Future development milestone payment the Company is eligible to receive					$ 80,000
Minimum | Collaboration Agreement with Bayer HealthCare LLC
Collaboration Agreements [Line Items]
Revenue based on percentage of annual sales in Japan				33.50%
Maximum | Collaboration Agreement with Bayer HealthCare LLC
Collaboration Agreements [Line Items]
Revenue based on percentage of annual sales in Japan				40.00%

Collaboration Agreements (EYLEA

Collaboration Agreements (EYLEA) (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended
	Aug. 31, 2007	Oct. 31, 2006	Mar. 31, 2014	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Collaboration Agreements [Line Items]
Period for Achieving Sales Target for Milestone Payment, Rolling Basis							12 months
Levels of twelve month sales at which sales milestone payments were received							$ 500,000
level of twelve months sales at which sales milestone payments maybe received - 100 million							100,000
Accounts receivable from Bayer HealthCare					$ 175,263	$ 162,152
Collaboration Agreement with Bayer HealthCare LLC
Collaboration Agreements [Line Items]
Percentage of repayment of development balance out of profits					50.00%
Contingent reimbursement obligation					$ 256,000
Revenue Recognition, Milestone Method, Revenue Recognized					0	15,000	105,000
Levels of twelve months sales at which sales milestone payments were received - 200 million						200,000
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned					$ 9,010	8,887	23,383
Minimum advance notice required to terminate collaboration agreement					6 months
Proceeds from Collaborators	$ 20,000	$ 75,000
Other Research and Development Expense					$ 1,400	$ 13,700	18,600
Deferred Revenue, Additions	$ 20,000	$ 75,000
maximum advance notice required to terminate collaboration agreement					12 months
BRVO
Collaboration Agreements [Line Items]
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned			$ 15,700
starting at sales achievement - $200 million
Collaboration Agreements [Line Items]
Period for Achieving Sales Target for Milestone Payment, Rolling Basis						12 months
starting at sales achievement - $500 million
Collaboration Agreements [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized							90,000
sales achievement - 200 million
Collaboration Agreements [Line Items]
Maximum amount of sales milestone payments if total sales achieve specific levels							$ 15,000
sales achievement - 100 million
Collaboration Agreements [Line Items]
Period for Achieving Sales Target for Milestone Payment, Rolling Basis							12 months
Maximum amount of sales milestone payments if total sales achieve specific levels						$ 15,000
Minimum | Collaboration Agreement with Bayer HealthCare LLC
Collaboration Agreements [Line Items]
Revenue based on percentage of annual sales in Japan				33.50%
Maximum | Collaboration Agreement with Bayer HealthCare LLC
Collaboration Agreements [Line Items]
Revenue based on percentage of annual sales in Japan				40.00%

Collaboration Agreements (PDGFR

Collaboration Agreements (PDGFR-beta Antibody) (Details) $ in Thousands	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Collaboration Agreements [Line Items]
Accounts receivable from Bayer HealthCare		$ 175,263	$ 162,152
PDGFR-beta outside the US
Collaboration Agreements [Line Items]
Maximum percentage of outstanding shares that may be acquired, under 'standstill' provisions		20.00%
Percentage of global development cost to be paid by the collaboration partner under the collaboration		25.00%
Percentage of development cost for the territory outside the United States to be paid for under the collaboration		50.00%
Percentage of development milestone payments to be reimbursed		50.00%
Number of development milestone payments the Company received				2
Deferred Revenue, Additions				$ 2,500
Substantive milestone payment to the Company			$ 5,000
Proceeds from Collaborators				$ 25,500
Ang2 Antibody [Member]
Collaboration Agreements [Line Items]
Percentage of global development cost to be paid by the collaboration partner under the collaboration	25.00%
Percentage of development cost for the territory outside the United States to be paid for under the collaboration	50.00%
Deferred Revenue, Additions	$ 50,000
Future development milestone payment the Company is eligible to receive		$ 80,000

Collaboration Agreements (Mitsu

Collaboration Agreements (Mitsubishi Tanabe Pharma) (Details) - Mitsubishi Tanabe Pharma Corporation (MTPC) [Member] - Collaborative Arrangement [Member] - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Mar. 31, 2016	Dec. 31, 2016
Collaboration Agreements [Line Items]
Deferred Revenue, Additions	$ 10
Deferred Revenue, Revenue Recognized			$ 14.4
Future development milestone payment the Company is eligible to receive			65
Contingent payments Company could receive			90
Collaborative Arrangement, Additional Eligible Aggregate Payments			100
Starting specified levels of annual sales at which sales milestone payments may be received			$ 200
Maximum
Collaboration Agreements [Line Items]
Collaborative Arrangement, Purchase Price, Percentage of Net Product Sales			50.00%
Minimum
Collaboration Agreements [Line Items]
Collaborative Arrangement, Purchase Price, Percentage of Net Product Sales			30.00%
First Payment [Member]
Collaboration Agreements [Line Items]
Deferred Revenue, Additions		$ 45
Second Payment [Member]
Collaboration Agreements [Line Items]
Deferred Revenue, Additions		$ 15

Collaboration Agreements (Teva

Collaboration Agreements (Teva Agreement) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Collaboration Agreements [Line Items]
Accounts and Notes Receivable, Net			$ 175,263	$ 162,152
Deferred revenue, current portion			231,664	153,487
Other Collaboration Revenue			744,270	$ 580,488	$ 495,555
Teva Pharmaceuticals [Member] | Collaborative Arrangement [Member]
Collaboration Agreements [Line Items]
Deferred Revenue, Additions	$ 250,000	$ 250,000
Collaborative Arrangement, Additional Eligible Aggregate Payments			1,890,000
Deferred Revenue, Revenue Recognized			37,900
Teva Pharmaceuticals [Member]
Collaboration Agreements [Line Items]
Aggregate future development milestone payments the Company is eligible to receive			$ 460,000

Collaboration Agreements (Intel

Collaboration Agreements (Intellia Therapeutics) (Details)	1 Months Ended	6 Months Ended	12 Months Ended
	Apr. 30, 2016USD ($)target	Jun. 30, 2016USD ($)shares	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Collaboration Agreements [Line Items]
Payments to Acquire Marketable Securities			$ 809,419,000	$ 557,105,000	$ 564,188,000
Intella Therapeutics [Member]
Collaboration Agreements [Line Items]
Upfront Payment Made	$ 75,000,000
Collaboration Agreement, Number of Targets Company Has Rights To | target	10
Collaboration Agreement, Extension Period	2 years
Investment obligation		$ 50,000,000
Shares of Common Stock Purchased | shares		2,777,777
Payments to Acquire Marketable Securities		$ 50,000,000

Collaboration Agreements (Adice

Collaboration Agreements (Adicet Bio) (Details) - USD ($) $ in Millions	1 Months Ended
	Jul. 31, 2016	Jul. 30, 2016
Collaboration Agreements [Line Items]
Period over which we have obligation		5 years
Adicet Bio [Member]
Collaboration Agreements [Line Items]
Other Research and Development Expense	$ 25

Technology Licensing Agreemen53

Technology Licensing Agreements (Details) - License Agreement with Astellas Pharma Inc. - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2010	Mar. 31, 2007	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Revenue Arrangement [Line Items]
Non-exclusive license agreement term		6 years
Advance payment received due to amended licensing agreement	$ 165
Recognition period for advance payment	7 years
Future payment to be made under terms of amended licensing agreement			$ 130
Number of days of advance written notice to terminate agreement			90 days
Technology licensing revenue			$ 23.6	$ 23.6	$ 23.6
Deferred Revenue			$ 33.9	$ 57.4

Marketable Securities (Details)

Marketable Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	$ 1,380,487	$ 856,429
Unrealized Gains	6,241	14,623
Unrealized (Losses)	(18,987)	(2,769)
Total fair value of available-for-sale marketable securities	1,367,741	868,283
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Maturities within one year	503,482	236,121
Maturities after one year through five years	815,040	600,695
Total	1,318,522	836,816
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months	883,950	731,331
Fair Value - 12 Months or Greater	36,407	23,749
Fair Value - Total	920,357	755,080
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months	(18,929)	(2,677)
Unrealized Loss- 12 Months or Greater	(58)	(92)
Unrealized Loss - Total	(18,987)	(2,769)
Available-for-sale Securities, Gross Realized Losses			$ 0
Corporate bonds
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months	759,222	668,199
Fair Value - 12 Months or Greater	36,407	23,749
Fair Value - Total	795,629	691,948
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months	(4,685)	(2,473)
Unrealized Loss- 12 Months or Greater	(58)	(92)
Unrealized Loss - Total	(4,743)	(2,565)
Corporate bonds | Unrestricted
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	1,076,964	770,092
Unrealized Gains	630	156
Unrealized (Losses)	(4,743)	(2,565)
Total fair value of available-for-sale marketable securities	1,072,851	767,683
U.S. government and government agency obligations
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months	81,170	51,215
Fair Value - 12 Months or Greater	0	0
Fair Value - Total	81,170	51,215
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months	(641)	(193)
Unrealized Loss- 12 Months or Greater	0	0
Unrealized Loss - Total	(641)	(193)
U.S. government and government agency obligations | Unrestricted
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	132,923	51,402
Unrealized Gains	58	0
Unrealized (Losses)	(641)	(193)
Total fair value of available-for-sale marketable securities	132,340	51,209
Municipal Bonds [Member]
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months	7,141	11,917
Fair Value - 12 Months or Greater	0	0
Fair Value - Total	7,141	11,917
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months	(20)	(11)
Unrealized Loss- 12 Months or Greater	0	0
Unrealized Loss - Total	(20)	(11)
Municipal Bonds [Member] | Unrestricted
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	7,663	17,930
Unrealized Gains	1	5
Unrealized (Losses)	(20)	(11)
Total fair value of available-for-sale marketable securities	7,644	17,924
Commercial Paper [Member] | Unrestricted
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	63,074
Unrealized Gains	1
Unrealized (Losses)	0
Total fair value of available-for-sale marketable securities	63,075
Certificates of Deposit [Member] | Unrestricted
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	42,612
Unrealized Gains	0
Unrealized (Losses)	0
Total fair value of available-for-sale marketable securities	42,612
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments	9,800	0	0
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months	36,417
Fair Value - 12 Months or Greater	0
Fair Value - Total	36,417
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months	(13,583)
Unrealized Loss- 12 Months or Greater	0
Unrealized Loss - Total	(13,583)
Equity Securities [Member] | Unrestricted
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	57,251	17,005
Unrealized Gains	5,551	14,462
Unrealized (Losses)	(13,583)	0
Total fair value of available-for-sale marketable securities	49,219	31,467
Significant Other Observable Inputs (Level 2)
Schedule of Available-for-sale Securities [Line Items]
Other than Temporary Impairment Losses, Investments	$ 0	$ 0	$ 0

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 31, 2011
Available-for-sale marketable securities:
Total fair value of available-for-sale marketable securities	$ 1,367,741,000	$ 868,283,000
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	44,100,000	91,400,000
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	0	0
Convertible Debt [Abstract]
Liabilities, Current	1,241,495,000	811,162,000
Convertible senior notes
Available-for-sale marketable securities:
Convertible Debt	0	$ 11,154,000
Convertible Debt [Abstract]
Interest rate, stated percentage		1.875%		1.875%
Fair value of the outstanding notes		$ 72,800,000
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other than Temporary Impairment Losses, Investments	0	0	$ 0
Significant Unobservable Inputs (Level 3)
Available-for-sale marketable securities:
Marketable Securities, Unrealized Gain (Loss)	0	0
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale marketable securities:
Total fair value of available-for-sale marketable securities	49,219,000	31,467,000
Measured on a recurring basis | Significant Other Observable Inputs (Level 2)
Available-for-sale marketable securities:
Total fair value of available-for-sale marketable securities	1,318,522,000	836,816,000
Measured on a recurring basis | Unrestricted | Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale marketable securities:
Financial Instruments, Owned, Corporate Debt, at Fair Value	0	0
U.S. government and government agency obligations	0	0
Municipal Debt Securities, at Carrying Value	0	0
Commercial Paper	0
Certificates of Deposit, at Carrying Value	0
Available-for-sale Securities, Equity Securities	49,219,000	31,467,000
Measured on a recurring basis | Unrestricted | Significant Other Observable Inputs (Level 2)
Available-for-sale marketable securities:
Financial Instruments, Owned, Corporate Debt, at Fair Value	1,072,851,000	767,683,000
U.S. government and government agency obligations	132,340,000	51,209,000
Municipal Debt Securities, at Carrying Value	7,644,000	17,924,000
Commercial Paper	63,075,000
Certificates of Deposit, at Carrying Value	42,612,000
Available-for-sale Securities, Equity Securities	0	0
Fair Value | Measured on a recurring basis
Available-for-sale marketable securities:
Total fair value of available-for-sale marketable securities	1,367,741,000	868,283,000
Fair Value | Measured on a recurring basis | Unrestricted
Available-for-sale marketable securities:
Financial Instruments, Owned, Corporate Debt, at Fair Value	1,072,851,000	767,683,000
U.S. government and government agency obligations	132,340,000	51,209,000
Municipal Debt Securities, at Carrying Value	7,644,000	17,924,000
Commercial Paper	63,075,000
Certificates of Deposit, at Carrying Value	42,612,000
Available-for-sale Securities, Equity Securities	$ 49,219,000	$ 31,467,000

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Raw materials	$ 92,287	$ 59,151
Work in process	202,301	132,068
Finished goods	13,334	11,197
Deferred costs	91,434	36,162
Total Inventories	399,356	238,578
Inventory write-downs and reserves	$ 14,000	$ 10,600	$ 6,000

Property, Plant, and Equipmen57

Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Land, Gross	$ 103,906	$ 77,826
Buildings and Improvements, Gross	1,278,283	760,517
Leasehold Improvements, Gross	101,101	95,226
Construction in Progress, Gross	318,929	579,834
Costs incurred by the landlord to construct new laboratory and office facilities	554,181	330,432
Furniture and Fixtures, Gross	152,525	81,381
Property, plant, and equipment, gross	2,508,925	1,925,216
Less: accumulated depreciation and amortization	(425,504)	(331,096)
Property, plant, and equipment, net	2,083,421	1,594,120
Depreciation and amortization expense	104,745	74,909	$ 52,686
Capital Lease Obligations, Current	127,274	0
Building and improvements
Property, Plant and Equipment [Line Items]
Buildings and Improvements, Gross	269,000	254,600
UNITED STATES
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, net	1,441,200	1,118,400
Foreign
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, net	642,200	475,700
Tarrytown, New York | Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Additions		$ 73,000
Tarrytown, New York
Property, Plant and Equipment [Line Items]
Capital Lease Obligations, Current	$ 138,100

Accounts Payable and Accrued 58

Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accounts payable	$ 134,984	$ 140,962
Accrued payroll and related costs	153,086	133,223
Accrued clinical trial expense	91,753	88,297
Accrued sales-related charges, deductions and royalties	159,985	195,986
Taxes Payable, Current	235,776	0
Other accrued expenses and liabilities	103,512	85,644
Accounts payable and accrued expenses	$ 879,096	$ 644,112

Deferred Revenue (Details)

Deferred Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current portion:
Deferred revenue, current portion	$ 231,664	$ 153,487
Deferred revenue - other, current portion	116,397	51,914
Long-term portion:
Deferred revenue, long-term portion	830,772	664,679
Deferred revenue - other	327,298	82,015
Received or receivable from Sanofi
Current portion:
Deferred revenue, current portion		101,573
Long-term portion:
Deferred revenue, long-term portion		582,664
Received or receivable from Bayer HealthCare
Current portion:
Deferred revenue, current portion	31,084	24,290
Long-term portion:
Deferred revenue, long-term portion	77,028	31,926
Mitsubishi Tanabe Pharma Corporation (MTPC) [Member]
Current portion:
Deferred revenue, current portion	9,188	2,352
Long-term portion:
Deferred revenue, long-term portion	45,940	7,059
Teva Pharmaceuticals [Member]
Current portion:
Deferred revenue, current portion	43,122	0
Long-term portion:
Deferred revenue, long-term portion	194,050	0
Received for technology license agreement
Current portion:
Deferred revenue, current portion	23,572	23,572
Long-term portion:
Deferred revenue, long-term portion	10,280	33,851
Other
Current portion:
Deferred revenue, current portion	9,431	1,700
Long-term portion:
Deferred revenue, long-term portion	$ 0	$ 9,179

Debt (Details)

Debt (Details) - USD ($)	1 Months Ended				3 Months Ended				12 Months Ended
	Nov. 30, 2015	Feb. 28, 2015	Nov. 30, 2014	Oct. 31, 2011	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Reclassification of warrants			493,229
Treasury Stock, Value					$ 316,240,000		$ 306,069,000		$ 316,240,000	$ 306,069,000
Net carrying amount of the liability component [Abstract]
Treasury Stock, Shares					3,763,868		3,642,820		3,763,868	3,642,820
Warrants [Abstract]
Adjustments to Additional Paid in Capital, Other									$ (643,365,000)	$ (449,456,000)	$ (294,552,000)
Payments for Repurchase of Warrants									643,365,000	573,487,000	294,552,000
Maximum amount of warrant payable										(23,317,000)	148,496,000
Maximum share price for warrant holders to close out hedge position	$ 535
Convertible Debt [Abstract]
Repayments of Convertible Debt									$ 12,894,000	$ 166,467,000	220,639,000
Stock Issued During Period, Shares, New Issues									121,058	1,625,113
Loss on Extinguishment of Debt										$ 18,861,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments									$ 47,789,000	819,657,000	691,869,000
Line of Credit Facility [Abstract]
Treasury Stock, Value, Acquired, Cost Method									0	$ 0	$ 0
November 2016 Agreement [Member] [Member]
Warrants [Abstract]
Payments for Repurchase of Warrants					$ 401,200,000
Warrant
Warrants [Abstract]
Strike price of the warrant transaction (in dollars per share)				$ 103.41
Proceeds received from the Warrant				$ 93,800,000
Reduction of number of warrants		416,480				360,406	115,970			898,547	1,220,745
Payments for Repurchase of Warrants		$ 124,000,000				$ 135,300,000	$ 50,000,000			$ 399,500,000	$ 294,600,000
Accounts Payable, Other											59,800,000
Liabilities, Fair Value Adjustment					$ 0		$ 0		$ 0	$ 0	87,500,000
February 2016 Agreement [Member]
Warrants [Abstract]
Reduction of number of warrants									403,665
Payments for Repurchase of Warrants									$ 106,900,000
Maximum reduction of warrants held by warrant holder									975,142
Maximum share price for warrant holders to close out hedge position									$ 375
Call option
Convertible Debt [Abstract]
Purchase of convertible note hedges				117,500,000
Convertible senior notes
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 400,000,000
Interest rate, stated percentage				1.875%			1.875%			1.875%
Initial conversion price (in dollars per share)				$ 84.02
Estimated fair value of the liability component				$ 271,100,000
Carrying amount of equity component				120,900,000
Gross proceeds from the issuance of the Notes				$ 392,000,000
Effective interest rate used to amortize the discount on the liability component					10.20%				10.20%
Net carrying amount of the liability component [Abstract]
Convertible Debt					$ 0		$ 11,154,000		$ 0	$ 11,154,000
Unamortized discount					0		(352,000)		0	(352,000)
Convertible Notes Payable					0		$ 10,802,000		0	10,802,000
Interest Expense, Debt [Abstract]
Contractual coupon interest rate									7,000	544,000	5,036,000
Amortization of discount and note issuance costs									150,000	2,818,000	17,821,000
Total interest expense									157,000	3,362,000	22,857,000
Credit Facility [Domain]
Line of Credit Facility [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity								$ 750,000,000
Line of Credit Facility, Expiration Period								5 years
Available increase to the credit facility								$ 250,000,000
Line of Credit Facility, Current Borrowing Capacity					100,000,000				100,000,000
Line of Credit Facility, Fair Value of Amount Outstanding					$ 0				0
Additional Paid-in Capital
Warrants [Abstract]
Adjustments to Additional Paid in Capital, Other								$ 23,300,000	(643,365,000)	(449,456,000)	(294,552,000)
Maximum amount of warrant payable										(23,317,000)	148,496,000
Convertible Debt [Abstract]
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments									47,789,000	819,657,000	691,869,000
Line of Credit Facility [Abstract]
Treasury Stock, Value, Acquired, Cost Method									10,171,000	136,539,000	169,530,000
Treasury Stock
Line of Credit Facility [Abstract]
Treasury Stock, Value, Acquired, Cost Method									$ (10,171,000)	$ (136,539,000)	$ (169,530,000)
Treasury Stock, Shares, Acquired									121,048	1,625,088	2,018,000

Commitments and Contingencies -

Commitments and Contingencies - Leases (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016USD ($)ft²	Dec. 31, 2016USD ($)ft²building	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Mar. 31, 2017USD ($)	Dec. 30, 2016USD ($)
Operating Leases [Abstract]
Facility Purchase Price						$ 720,000
Commitments under operating leases [Abstract]
2,017	$ 9,884	$ 9,884
2,018	5,685	5,685
2,019	5,090	5,090
2,020	4,283	4,283
2,021	3,993	3,993
Thereafter	22,336	22,336
Total	$ 51,271	51,271
Rent expense under operating leases [Abstract]
Rent expense under operating leases		$ 16,713	$ 15,202	$ 14,312
Tarrytown lease [Abstract]
Net Rentable Area | ft²	300,000	300,000
Payment towards purchase price	$ 57,000	$ 57,000
Capital Leases, Future Minimum Payments Due	$ 448,494	448,494
Intended Facility Financing						$ 720,000
Initial term of lease	5 years
Facilities
Commitments under operating leases [Abstract]
2,017	$ 4,728	4,728
2,018	4,860	4,860
2,019	4,817	4,817
2,020	4,271	4,271
2,021	3,982	3,982
Thereafter	22,336	22,336
Total	44,994	44,994
Rent expense under operating leases [Abstract]
Rent expense under operating leases		15,861	14,659	13,360
Equipment
Commitments under operating leases [Abstract]
2,017	5,156	5,156
2,018	825	825
2,019	273	273
2,020	12	12
2,021	11	11
Thereafter	0	0
Total	$ 6,277	6,277
Rent expense under operating leases [Abstract]
Rent expense under operating leases		$ 852	$ 543	$ 952
Facilities Building D and E
Operating Leases [Abstract]
Number of new buildings leased | building		2
Subsequent Event [Member]
Tarrytown lease [Abstract]
Expected reimbursement of payment made					$ 57,000

Commitments and Contingencies62

Commitments and Contingencies - Capital Leases (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Capital Leased Assets [Line Items]
Capital Lease Obligations Incurred	$ 0
Capital Lease Obligations, Current	$ 127,274,000	$ 0

Commitments and Contingencies63

Commitments and Contingencies - Facility Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Facility Leases [Line Items]
2,017	$ 32,117
2,018	33,141
2,019	33,942
2,020	34,763
2,021	35,603
Thereafter	278,928
Total	448,494
Facility lease obligations [Abstract]
Interest expense in connection with facility lease obligation	5,400	$ 9,700	$ 14,500
Commitments under facility leases [Abstract]
Facility lease obligation, including reimbursements	353,852	364,708
Facilities - Buildings A and B
Schedule of Facility Leases [Line Items]
2,017	13,965
2,018	14,242
2,019	14,526
2,020	14,818
2,021	15,116
Thereafter	101,010
Total	$ 173,677
Facility lease obligations [Abstract]
Imputed interest rate applicable to facility lease obligation	12.00%
Commitments under facility leases [Abstract]
Facility lease obligation, including reimbursements	$ 99,323	108,857
Facilities - Building C
Schedule of Facility Leases [Line Items]
2,017	4,740
2,018	4,873
2,019	5,009
2,020	5,149
2,021	5,292
Thereafter	48,801
Total	$ 73,864
Facility lease obligations [Abstract]
Imputed interest rate applicable to facility lease obligation	11.00%
Commitments under facility leases [Abstract]
Facility lease obligation, including reimbursements	$ 44,338	49,475
Facilities Building D and E
Schedule of Facility Leases [Line Items]
2,017	12,922
2,018	13,267
2,019	13,621
2,020	13,983
2,021	14,354
Thereafter	121,927
Total	$ 190,074
Facility lease obligations [Abstract]
Imputed interest rate applicable to facility lease obligation	7.00%
Commitments under facility leases [Abstract]
Facility lease obligation, including reimbursements	$ 194,037	206,376
Facilities Building F [Member]
Schedule of Facility Leases [Line Items]
2,017	490
2,018	759
2,019	786
2,020	813
2,021	841
Thereafter	7,190
Total	$ 10,879
Facility lease obligations [Abstract]
Imputed interest rate applicable to facility lease obligation	10.00%
Commitments under facility leases [Abstract]
Facility lease obligation, including reimbursements	$ 16,154	$ 0

Commitments and Contingencies64

Commitments and Contingencies - Research Collaboration and Licensing Agreements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012
Agreements with Royalty Provisions
Research Collaboration and Licensing Arrangements [Line Items]
Royalty rate minimum	0.50%
Royalty rate maximum	16.50%
Royalty expense	$ 125.3	$ 247.9	$ 169.9
License agreement with Genentech - EYLEA
Research Collaboration and Licensing Arrangements [Line Items]
First payment made or maybe made upon reaching minimum sales target	60			$ 60
Cumulative relevant sales minimum sales target				$ 400
Cumulative sales range, 1st tier minimum	400
Sales range maximum 1st tier	3,000
Cumulative sales range, 2nd tier minimum	$ 3,000
Royalty payment percentage of cumulative sales within cumulative sales range	4.75%
Royalty payment percentage of cumulative sales over range	5.50%

Stockholders' Equity (Details)

Stockholders' Equity (Details)	1 Months Ended		12 Months Ended
	Oct. 31, 2011USD ($)	Dec. 31, 2007shares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)shares
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares) | shares			30,000,000	30,000,000
Number of demand rights to require the Company to conduct registered underwritten public offering			3
Repayments of Convertible Debt			$ 12,894,000	$ 166,467,000	$ 220,639,000
Gains (Losses) on Extinguishment of Debt				18,861,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments			47,789,000	819,657,000	691,869,000
Payments for Repurchase of Warrants			$ 643,365,000	573,487,000	294,552,000
Maximum amount of warrant payable				$ (23,317,000)	$ 148,496,000
Call option
Class of Stock [Line Items]
Purchase of convertible note hedges	$ 117,500,000
Convertible senior notes
Class of Stock [Line Items]
Total convertible senior notes - par	$ 400,000,000
Sanofi
Class of Stock [Line Items]
Number of shares of Common Stock purchased | shares		12,000,000
Maximum percentage of outstanding shares that may be acquired, under 'standstill' provisions			30.00%
Percentage Of Outstanding Shares Or Voting Rights Under Amended Investor Agreement			20.00%
Percentage Of Outstanding Shares that the Company is required to appoint an individual agreed upon by the Company and the Collaborator to the Company's board of directors			20.00%
Class A Stock
Class of Stock [Line Items]
Common Stock, shares authorized (in shares) | shares			40,000,000	40,000,000
Common Stock, par value (in dollars per share) | $ / shares			$ 0.001	$ 0.001
Common Stock, voting rights			ten votes per share
Common Stock
Class of Stock [Line Items]
Common Stock, shares authorized (in shares) | shares			320,000,000	320,000,000	160,000,000
Common Stock, par value (in dollars per share) | $ / shares			$ 0.001	$ 0.001
Common Stock, voting rights			one vote per share
Debt Conversion, Converted Instrument, Shares Issued | shares			121,000	1,625,000	2,018,000
Bayer Collaboration Agreement - PDGFR-beta outside the US
Class of Stock [Line Items]
Maximum percentage of outstanding shares that may be acquired, under 'standstill' provisions			20.00%
Teva Pharmaceuticals [Member]
Class of Stock [Line Items]
Maximum percentage of outstanding shares that may be acquired, under 'standstill' provisions			5.00%
maximum percentage of voting power			30.00%
Maximum percentage of voting power that may be acquired by another party			10.00%
Additional Paid-in Capital
Class of Stock [Line Items]
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments			$ 47,789,000	$ 819,657,000	$ 691,869,000
Maximum amount of warrant payable				$ (23,317,000)	$ 148,496,000

Long-Term Incentive Plans (Deta

Long-Term Incentive Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of awards	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of shares outstanding at beginning of period	23,165,769
Number of shares granted	4,201,978	4,495,487	3,913,368
Number of shares forfeited	(468,798)
Number of shares expired	(20,645)
Number of shares exercised	(1,742,277)
Number of shares outstanding at end of period	25,136,027	23,165,769
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average exercise price - outstanding at beginning of period	$ 236.75
Weighted average exercise price - granted	386.44	$ 537.29	$ 385.33
Weighted average exercise price - forfeited	398.57
Weighted average exercise price - expired	420.04
Weighted average exercise price - exercised	76.79
Weighted average exercise price - outstanding at end of period	$ 269.69	$ 236.75
Weighted average remaining contractual term (in years) - outstanding	6 years 7 months 28 days
Instrinsic value - outstanding	$ 3,399,815
Number of shares vested and expected to vest	24,598,430
Weighted average execise price - vested and expected to vest	$ 266.16
Weighted average remaining contractual term - vested and expected to vest	6 years 7 months 6 days
Intrinsic value - vested and expected to vest	$ 3,397,437
Number of shares exercisable	15,140,287
Weighted average exercise price - exercisable	$ 166.96
Weighted average remaining contractual term - exercisable	5 years 2 months 9 days
Intrinsic value - exercisable	$ 3,299,296
Total intrinsic value - of stock options exercised	$ 550,400	$ 1,031,600	$ 1,081,200
Exercise Price Equal to Market Price [Abstract]
Number of Options Granted (shares)	4,201,978	4,495,487	3,913,368
Weighted Average Exercise Price (dollars per share)	$ 386.44	$ 537.29	$ 385.33
Weighted Average Fair Value	$ 126.68	$ 181.65	$ 140.38
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected volatility	34.00%	35.00%	39.00%
Expected lives from grant date	5 years 1 month 1 day	5 years 1 month 1 day	5 years 2 months 11 days
Expected dividend yield	0.00%	0.00%	0.00%
Risk-free interest rate	1.84%	1.68%	1.62%
Stock options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Stock options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Phantom stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period within vesting date that awards may be received	30 days
Non-performance based stock options
Exercise Price Equal to Market Price [Abstract]
Non-cash stock-based compensation expense	$ 546,000	$ 443,700	$ 306,100
Unrecognized stock-based compensation cost, net of estimated forfeitures	$ 888,000
Weighted average period for recognition of total unrecognized compensation expense (in years)	1 year 11 months
Performance-based stock options
Exercise Price Equal to Market Price [Abstract]
Non-cash stock-based compensation expense			4,100
Restricted stock
Exercise Price Equal to Market Price [Abstract]
Non-cash stock-based compensation expense	$ 13,900	$ 15,300	$ 11,500
Unrecognized stock-based compensation cost, net of estimated forfeitures	$ 26,000
Weighted average period for recognition of total unrecognized compensation expense (in years)	1 year 2 months
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Number of shares outstanding at beginning of period	541,700
Number of shares granted	16,750
Number of shares vested	(11,590)
Number of shares forfeited	(40)
Number of shares outstanding at end of period	546,820	541,700
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Weighted average grant date fair value at beginning of period	$ 133.96
Weighted average grant date fair value - granted	385.84
Weighted average grant date fair value - vested	125.38
Weighted average grant date fair value - forfeited	237.68
Weighted average grant date fair value at end of period	$ 141.85	$ 133.96
Long-Term Incentive Plan 2000 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance				35,397,043
Long-Term Incentive Plan 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance			16,485,333
Number of shares available for future grants	6,408,989
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of shares exercised	(1,697,000)	(2,457,000)	(3,468,000)
Common Stock | Long-Term Incentive Plan 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance			4,485,333

Employee Savings Plan (Details)

Employee Savings Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contribution expense to 401(k) Savings Plan	$ 17.7	$ 15.4	$ 13.1

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Income before income taxes		$ 1,329,815	$ 1,225,097	$ 761,235
Current:
Federal		786,964	686,561	437,038
State		8,769	28,568	28,718
Current Foreign Tax Expense (Benefit)		(1,362)	4,004	2,879
Total current tax expense		794,371	719,133	468,635
Deferred:
Federal		(377,368)	(119,849)	(62,932)
State		13,431	(3,768)	18,891
Deferred Foreign Income Tax Expense (Benefit)		3,859	(6,475)	(1,485)
Total deferred tax (benefit) expense		(360,078)	(130,092)	(45,526)
Total income tax expense (benefit)		$ 434,293	$ 589,041	$ 423,109
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
U.S. federal statutory tax rate		35.00%	35.00%	35.00%
Stock-based compensation		(10.90%)	(0.00%)	(0.00%)
State and local income taxes		0.30%	1.00%	2.40%
Change in state effective rate		1.00%	(0.10%)	2.90%
Foreign income tax rate differential		8.80%	12.20%	15.80%
Income tax credits		(1.20%)	(1.60%)	(5.10%)
Non-deductible Branded Prescription Drug Fee		1.90%	2.00%	2.80%
Domestic production activities deduction		(2.80%)	(3.20%)	(0.00%)
Other permanent differences		0.60%	2.80%	1.80%
Effective income tax rate		32.70%	48.10%	55.60%
Deferred tax assets:
Net operating loss carryforward		$ 137	$ 140
Fixed and intangible assets		21,139	0
Deferred revenue		214,587	51,766
Deferred compensation		515,984	349,508
Capitalized research and development costs		2,492	7,725
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities		37,188	47,520
Other		46,471	26,580
Deferred tax assets, gross		837,998	483,239
Valuation allowance		(3,420)	0
Deferred tax assets, net		834,578	483,239
Deferred tax liabilities:
Accruals		0	(3,280)
Deferred Tax Liabilities, Property, Plant and Equipment		0	(5,559)
Deferred Tax Liabilities, Other		(9,275)	(12,455)
Deferred tax liabilities, gross		(9,275)	(21,294)
Deferred Tax Assets, Net		825,303	461,945
Utilization of net operating loss carryforwards related to exercises of Nonqualified Stock Options and disqualifying dispositions of ISOs, credited to additional paid-in capital			405,317	$ 439,278
Excess Tax Benefit from Share-based Compensation, Financing Activities		0	405,317	439,278
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		107,200	102,100	51,200
Other Comprehensive Income (Loss), Tax		3,300	24,900	27,100
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1	$ 116,572	116,572	57,615	26,627
Gross increases related to current year tax positions		45,575	59,909	27,538
Unrecognized Tax Benefits, Period Increase (Decrease)		(42,284)	(952)	6,464
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities		2,697	0	3,014
Balance as of December 31		117,166	116,572	57,615
Unrecognized Tax Benefits, Interest on Income Taxes Accrued		3,300
Decrease in Unrecognized Tax Benefits is Reasonably Possible		22,300
UNITED STATES
Operating Loss Carryforwards [Line Items]
Income before income taxes		1,650,959	1,665,087	1,101,446
Foreign
Operating Loss Carryforwards [Line Items]
Income before income taxes		(321,144)	(439,990)	(340,211)
Accounting Standards Update 2016-09 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Deferred tax liabilities:
Excess Tax Benefit from Share-based Compensation, Financing Activities		$ 144,800
Additional Paid-in Capital
Deferred tax liabilities:
Utilization of net operating loss carryforwards related to exercises of Nonqualified Stock Options and disqualifying dispositions of ISOs, credited to additional paid-in capital			$ 405,317	$ 439,278
Additional Paid-in Capital | Accounting Standards Update 2016-09 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Deferred tax liabilities:
Excess Tax Benefit from Share-based Compensation, Financing Activities	$ 15,600

Legal Matters Legal Matters (De

Legal Matters Legal Matters (Details)	12 Months Ended
	Dec. 31, 2016EUR (€)
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, per unit produced.	€ 10,000
Loss Contingency, Damages Sought, Value	€ 10,000,000

Net Income (Loss) Per Share (De

Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net income	$ 253,115	$ 264,804	$ 196,218	$ 181,385	$ 154,994	$ 210,398	$ 194,643	$ 76,021	$ 895,522	$ 636,056	$ 338,126
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities									397	0	0
Net Income (Loss) Attributable to Parent, Diluted									$ 895,919	$ 636,056	$ 338,126
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average shares outstanding - basic									104,719	103,061	100,612
Effect of dilutive securities (in shares):
Stock options									10,177	9,446	9,440
Restricted stock									474	477	425
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities									61	0	0
Warrants									936	2,246	2,936
Dilutive potential shares									11,648	12,169	12,801
Weighted average shares - diluted (in shares)									116,367	115,230	113,413
Earnings Per Share, Basic and Diluted [Abstract]
Net income per share - basic (in USD per shares)	$ 2.41	$ 2.53	$ 1.88	$ 1.74	$ 1.49	$ 2.04	$ 1.89	$ 0.74	$ 8.55	$ 6.17	$ 3.36
Net income per share - diluted (in USD per shares)	$ 2.19	$ 2.27	$ 1.69	$ 1.59	$ 1.34	$ 1.82	$ 1.69	$ 0.66	$ 7.70	$ 5.52	$ 2.98
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares									8,041	1,343	1,470
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares									19	0	0
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares									0	994	4,247

Statement of Cash Flows (Detail

Statement of Cash Flows (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accrued capital expenditures	$ 28,200,000	$ 50,700,000	$ 56,200,000
Capital Lease Obligations, Current	127,274,000	0
Facilities Building D and E
Facility lease obligations recognized	16,800,000	26,000,000	127,800,000
Warrant
Liabilities, Fair Value Adjustment	0	$ 0	$ 87,500,000
Tarrytown, New York
Capital Lease Obligations, Current	$ 138,100,000

Unaudited Quarterly Results (De

Unaudited Quarterly Results (Details) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016USD ($)$ / shares	Sep. 30, 2016USD ($)$ / shares	Jun. 30, 2016USD ($)$ / shares	Mar. 31, 2016USD ($)$ / shares	Dec. 31, 2015USD ($)$ / shares	Sep. 30, 2015USD ($)$ / shares	Jun. 30, 2015USD ($)$ / shares	Mar. 31, 2015USD ($)$ / shares	Dec. 31, 2016USD ($)$ / shares	Dec. 31, 2015USD ($)$ / shares	Dec. 31, 2014USD ($)$ / shares	Dec. 31, 2013
Quarterly Financial Information Disclosure [Line Items]
Excess tax benefit from stock-based compensation									$ 0	$ 405,317	$ 439,278
Revenues	$ 1,226,827	$ 1,220,122	$ 1,212,629	$ 1,200,849	$ 1,098,077	$ 1,137,422	$ 998,617	$ 869,612	4,860,427	4,103,728	2,819,557
Net income	$ 253,115	$ 264,804	$ 196,218	$ 181,385	$ 154,994	$ 210,398	$ 194,643	$ 76,021	$ 895,522	$ 636,056	$ 338,126
Net income per share - basic (in USD per shares) | $ / shares	$ 2.41	$ 2.53	$ 1.88	$ 1.74	$ 1.49	$ 2.04	$ 1.89	$ 0.74	$ 8.55	$ 6.17	$ 3.36
Net income per share - diluted (in USD per shares) | $ / shares	$ 2.19	$ 2.27	$ 1.69	$ 1.59	$ 1.34	$ 1.82	$ 1.69	$ 0.66	$ 7.70	$ 5.52	$ 2.98
Antibody Collaboration
Quarterly Financial Information Disclosure [Line Items]
Number of families of novel antibodies												2
Accounting Standards Update 2016-09 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Quarterly Financial Information Disclosure [Line Items]
Excess tax benefit from stock-based compensation									$ 144,800
Accounting Standards Update 2016-09 [Member] | Additional Paid-in Capital | New Accounting Pronouncement, Early Adoption, Effect [Member]
Quarterly Financial Information Disclosure [Line Items]
Excess tax benefit from stock-based compensation				$ 15,600