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Three Months Ended March 31,

(Shares in thousands)

Stock options

Convertible senior notes

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2015	Apr. 16, 2015
Entity Information [Line Items]
Entity Registrant Name	REGENERON PHARMACEUTICALS INC
Entity Central Index Key	0000872589
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	false
Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		101,305,623
Class A Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		1,971,868

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 507,907	$ 648,719
Marketable securities	234,257	251,761
Accounts receivable - trade, net	1,015,962	739,379
Accounts Receivable from Sanofi	159,444	121,058
Accounts receivable from Bayer HealthCare	163,056	156,962
Inventories	133,863	128,861
Deferred tax assets	62,126	49,235
Prepaid expenses and other current assets	34,099	71,486
Total current assets	2,310,714	2,167,461
Marketable securities	483,305	460,154
Property, plant, and equipment, at cost, net of accumulated depreciation and amortization	1,110,597	974,309
Deferred tax assets	289,484	289,021
Other assets	4,473	3,034
Total assets	4,198,573	3,893,979
Current liabilities:
Accounts payable and accrued expenses	462,762	483,489
Deferred revenue from Sanofi, current portion	19,342	15,927
Deferred revenue - other, current portion	51,845	58,098
Other Liabilities, Current	2,185	97,146
Total current liabilities	536,134	654,660
Deferred revenue from Sanofi	48,656	72,367
Deferred Revenue - other	114,318	103,909
Facility lease obligations	328,394	310,938
Convertible senior notes	144,082	146,773
Other long-term liabilities	55,559	40,855
Total liabilities	1,227,143	1,329,502
Stockholders' equity:
Preferred Stock	0	0
Additional paid-in capital	2,812,573	2,465,008
Retained earnings	292,665	216,644
Accumulated other comprehensive income	47,904	52,251
Treasury stock	(181,817)	(169,530)
Total stockholders' equity	2,971,430	2,564,477
Total liabilities and stockholders' equity	4,198,573	3,893,979
Class A Stock
Stockholders' equity:
Common stock	2	2
Common Stock
Stockholders' equity:
Common stock	$ 103	$ 102

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2015	Dec. 31, 2014
Stockholders' equity:
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)	2,163,980	2,017,732
Class A Stock
Stockholders' equity:
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)	1,971,868	1,973,368
Common Stock, shares outstanding (in shares)	1,971,868	1,973,368
Common Stock
Stockholders' equity:
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	160,000,000	160,000,000
Common Stock, shares issued (in shares)	103,418,736	102,475,154

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revenues:
Net product sales	$ 544,573	$ 362,378
Sanofi collaboration revenue	173,356	130,508
Bayer HealthCare collaboration revenue	123,846	125,312
Technology licensing and other revenue	27,837	7,542
Total revenues	869,612	625,740
Expenses:
Research and development	343,113	287,379
Selling, general, and administrative	158,991	103,227
Cost of goods sold	42,570	27,473
Cost of collaboration and contract manufacturing	41,385	16,099
Total expenses	586,059	434,178
Income from operations	283,553	191,562
Other income (expense):
Investment and other income	81	937
Interest expense	(6,169)	(11,613)
Loss on extinguishment of debt	(942)	0
Total other income (expense)	(7,030)	(10,676)
Income before income taxes	276,523	180,886
Income tax expense	(200,502)	(112,581)
Net income	$ 76,021	$ 68,305
Net income per share - basic	$ 0.74	$ 0.69
Net income per share - diluted	$ 0.66	$ 0.61
Weighted average shares outstanding - basic	102,227	98,709
Weighted average shares outstanding - diluted	114,519	112,151
Statements of Comprehensive Income
Net income	$ 76,021	$ 68,305
Other comprehensive (loss) income:
Unrealized (loss) gain on marketable securities, net of tax	(4,347)	2,653
Comprehensive income	$ 71,674	$ 70,958

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$ 76,021	$ 68,305
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	16,027	11,530
Non-cash compensation expense	103,759	75,785
Non-cash interest expense	2,358	5,916
Losses on Extinguishment of Debt	942	0
Other non-cash charges and expenses, net	6,006	3,761
Deferred Taxes	(10,888)	(5,761)
Changes in assets and liabilites
Increase in Sanofi, Bayer HealthCare, and trade accounts receivable	(321,063)	(92,529)
Increase in Inventories	(5,932)	(15,550)
Decrease (increase) in prepaid expenses and other assets	35,874	(20,898)
(Decrease) increase in deferred revenue	(16,140)	37,107
Increase (decrease) in accounts payable, accrued expenses and other liabilities	25,534	(14,139)
Total adjustments	(163,523)	(14,778)
Net cash (used in) provided by operating activities	(87,502)	53,527
Cash flows from investing activities:
Purchases of marketable securities	(95,775)	(253,878)
Sales or maturities of marketable securities	80,456	82,469
Capital expenditures	(114,162)	(64,822)
Net cash used in investing activities	(129,481)	(236,231)
Cash flows from financing activities:
Proceeds (payments) in connection with facility and capital lease obligations	6,738	(262)
Repayments of convertible senior notes	(16,686)	0
Payments in connection with deduction of outstanding warrants	(124,531)	0
Proceeds from issuance of Common Stock	76,273	55,042
Payments in connection with Common Stock tendered for employee tax obligations	(21,192)	(63,086)
Excess tax benefit from stock-based compensation	155,569	117,260
Net cash provided by financing activities	76,171	108,954
Net decrease in cash and cash equivalents	(140,812)	(73,750)
Cash and cash equivalents at beginning of period	648,719	535,608
Cash and cash equivalents at end of period	$ 507,907	$ 461,858

Interim Financial Statements (Notes)	3 Months Ended
Interim Financial Statements (Notes)	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Interim Financial Statements	Interim Financial Statements The interim Condensed Consolidated Financial Statements of Regeneron Pharmaceuticals, Inc. ("Regeneron" or the "Company") have been prepared in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all information and disclosures necessary for a presentation of the Company's financial position, results of operations, and cash flows in conformity with accounting principles generally accepted in the United States of America. In the opinion of management, these financial statements reflect all normal recurring adjustments and accruals necessary for a fair statement of the Company's financial position, results of operations, and cash flows for such periods. The results of operations for any interim periods are not necessarily indicative of the results for the full year. The December 31, 2014 Condensed Consolidated Balance Sheet data were derived from audited financial statements, but do not include all disclosures required by accounting principles generally accepted in the United States of America. These financial statements should be read in conjunction with the financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014. Certain reclassifications have been made to prior period amounts to conform with the current period’s presentation. In addition, the previously issued (i) Consolidated Balance Sheet as of December 31, 2014 contained in the Company's Annual Report on Form 10-K for the year ended December 31, 2014, and (ii) Condensed Consolidated Statement of Operations and Comprehensive Income for the three months ended March 31, 2014 and Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2014 contained in the Company's Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2014, have each been revised in this Quarterly Report on Form 10-Q to reflect a correction in the Company's accounting for certain stock option awards. See Note 4.

Net Product Sales (Notes)

3 Months Ended

Mar. 31, 2015

Revenues [Abstract]

Product Sales and Concentration Risk [Text Block]

Product Sales

EYLEA^® net product sales in the United States totaled $541.1 million and $359.0 million for the three months ended March 31, 2015 and 2014, respectively. In addition, ARCALYST^® net product sales totaled $3.5 million and $3.4 million for the three months ended March 31, 2015 and 2014, respectively.

For the three months ended March 31, 2015 and 2014, the Company recorded 69% and 79%, respectively, of its total gross product revenue from sales to Besse Medical, a subsidiary of AmerisourceBergen Corporation.

Revenue from product sales is recorded net of applicable provisions for rebates and chargebacks under governmental programs, distribution-related fees, and other sales-related deductions. The following table summarizes the provisions, and credits/payments, for these sales-related deductions during the three months ended March 31, 2015 and 2014.



	Rebates & Chargebacks			Distribution- Related Fees			Other Sales- Related Deductions			Total
Balance as of December 31, 2014	$	3,083		$	21,166		$	532		$	24,781
Provision related to current period sales	11,353			24,781			1,383			37,517
Credits/payments	(9,779		)	(13,036		)	(1,411		)	(24,226		)
Balance as of March 31, 2015	$	4,657		$	32,911		$	504		$	38,072

Balance as of December 31, 2013	$	4,400		$	19,663		$	538		$	24,601
Provision related to current period sales	6,886			16,858			448			24,192
Credits/payments	(6,664		)	(16,310		)	(454		)	(23,428		)
Balance as of March 31, 2014	$	4,622		$	20,211		$	532		$	25,365

Collaboration Agreements (Notes)

3 Months Ended

Mar. 31, 2015

Collaboration Agreement [Abstract]

Collaboration Agreements

a. Sanofi

Sanofi collaboration revenue, as detailed below, consisted primarily of (i) recognition of previously deferred revenue related to the companies' ZALTRAP^® collaboration agreement, and (ii) reimbursement for research and development expenses that the Company incurred, partly offset by sharing of pre-launch commercialization expenses, in connection with the companies' antibody collaboration.



	Three Months Ended March 31,
Sanofi Collaboration Revenue	2015			2014
ZALTRAP:
Regeneron's share of losses in connection with commercialization of ZALTRAP	—			$	(3,212	)
Reimbursement of Regeneron research and development expenses	$	686		1,092
Other	15,236			2,177
Total ZALTRAP	15,922			57
Antibody:
Reimbursement of Regeneron research and development expenses	168,820			126,822
Reimbursement of Regeneron commercialization-related expenses	8,458			—
Regeneron's share of losses in connection with commercialization of antibodies	(22,405		)	—
Other	2,561			3,629
Total Antibody	157,434			130,451
	$	173,356		$	130,508

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 (ziv-aflibercept) Injection for Intravenous Infusion, in combination with 5-fluorouracil, leucovorin, irinotecan ("FOLFIRI"), for patients with metastatic colorectal cancer ("mCRC") that is resistant to or has progressed following an oxaliplatin-containing regimen, in the United States in the third quarter of 2012 and in certain European and other countries in the first quarter of 2013.

In February 2015, the Company and Sanofi entered into an amended and restated ZALTRAP agreement ("Amended ZALTRAP Agreement"), with an effective date of July 1, 2014. Under the terms of the Amended ZALTRAP Agreement, Sanofi will be solely responsible for the development and commercialization of ZALTRAP for cancer indications worldwide. Sanofi will bear the cost of all development and commercialization activities and will reimburse Regeneron for its costs for any such activities. Sanofi will pay 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. In addition, Regeneron no longer has a contingent contractual obligation to reimburse Sanofi for 50% of the development expenses that Sanofi previously funded for the development of ZALTRAP under the ZALTRAP Collaboration Agreement. 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 previously 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 exists, and (ii) the unamortized portion of up-front payments from Sanofi as the Company has no further performance obligations. In addition, in the first quarter of 2015, the Company recorded $19.8 million in technology licensing and other revenue, primarily related to (i) revenues earned from Sanofi based on a percentage of net sales of ZALTRAP and (ii) revenues earned from Sanofi for manufacturing ZALTRAP commercial supplies.

Antibodies

Under the Company's antibody collaboration agreement with Sanofi, agreed upon worldwide research and 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. During the three months ended March 31, 2015 and 2014, the Company recognized as additional research and development expense $25.0 million and $23.8 million, respectively, of antibody development expenses that the Company was obligated to reimburse to Sanofi related to Praluent^® and sarilumab.

Effective in the second and fourth quarters of 2014, the Company and Sanofi began sharing pre-launch commercialization expenses related to Praluent and sarilumab, respectively, in accordance with the companies’ antibody collaboration agreement.

In May 2013, the Company acquired from Sanofi full exclusive rights to antibodies targeting the platelet derived growth factor (PDGF) family of receptors and ligands in opthalmology. With respect to PDGF antibodies, the Company made two $5.0 million development milestone payments to Sanofi in the first quarter of 2014, which were recorded as research and development expense. The Company is also obligated to pay up to $30.0 million in additional potential development milestones as well as royalties on any future sales of PDGF antibodies.

b. Bayer HealthCare LLC

The Company and Bayer HealthCare globally collaborate on the development and commercialization of EYLEA outside of the United States. In addition, in January 2014, the Company entered into a license and collaboration agreement with Bayer HealthCare governing the joint development and commercialization outside the United States of an antibody product candidate to Platelet Derived Growth Factor Receptor Beta (PDGFR-beta).

The collaboration revenue the Company earned from Bayer HealthCare is detailed below:



	Three Months Ended March 31,
Bayer HealthCare Collaboration Revenue	2015		2014
EYLEA:
Regeneron's net profit in connection with commercialization of EYLEA outside the United States	$	89,426	$	61,159
Sales milestones	15,000		30,000
Cost-sharing of Regeneron EYLEA development expenses	2,657		20,347
Other	12,912		10,932
Total EYLEA	119,995		122,438
PDGFR-beta antibody:
Cost-sharing of REGN2176-3 development expenses	1,254		513
Other	2,597		2,361
Total PDGFR-beta	3,851		2,874
Total Bayer HealthCare collaboration revenue	$	123,846	$	125,312

EYLEA outside the United States

In the first quarter of 2015, the Company earned a $15.0 million sales milestone from Bayer HealthCare upon total aggregate net sales of specific commercial supplies of EYLEA outside the United States exceeding $200 million over a twelve-month period. In the first quarter of 2014, the Company earned two $15.0 million sales milestones from Bayer HealthCare upon total aggregate net sales of EYLEA outside the United States exceeding $500 million and $600 million, respectively, over a twelve-month period.

In January 2014, Bayer HealthCare decided to participate in the global development and commercialization of EYLEA outside the United States for the treatment of macular edema following branch retinal vein occlusion ("BRVO"). In connection with this decision, Bayer HealthCare 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 HealthCare 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.

PDGFR-beta antibody outside the United States

In January 2014, the Company entered into an agreement with Bayer HealthCare governing the joint development and commercialization outside the United States of an antibody product candidate to PDGFR-beta, including in combination with EYLEA, for the treatment of ocular diseases or disorders. In connection with the agreement, Bayer HealthCare made a $25.5 million non-refundable upfront 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. The $25.5 million upfront payment was initially recorded as deferred revenue, and will be recognized as revenue over the related performance period. Bayer HealthCare is also 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, as described above. In that regard, Bayer HealthCare made two $2.5 million development milestone payments to the Company in the first quarter of 2014 (both of which, for the purpose of revenue recognition, were not considered substantive).

Stock-based Compensation (Notes)

3 Months Ended

Mar. 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

Stock-based Compensation

The Company recognizes stock-based compensation expense for grants of stock option awards and restricted stock under the Company's 2014 Long-Term Incentive Plan based on the grant-date fair value of those awards. The Company recognized stock-based compensation expense of $103.8 million and $75.8 million in the first quarter of 2015 and 2014, respectively.

Revisions of Previously-Issued Financial Statements

During the first quarter of 2015, the Company determined that for certain stock option awards granted to an employee in prior periods, the incorrect requisite service period was utilized in determining the period over which the related compensation expense should have been recorded. Such awards were made as part of the Company's annual employee option grants in December of each applicable year. As a result, compensation expense for the three months and years ended December 31, 2014 and 2013 was understated, and compensation expense for the three months ended March 31, 2014 and 2013, June 30, 2014 and 2013, and September 30, 2014 and 2013 was overstated. These revisions consisted entirely of non-cash adjustments, and therefore had no impact on the Company's previously reported total cash flows from operating activities and total cash flows in its Statements of Cash Flows. The Company evaluated the impact of these items on prior periods, assessing materiality quantitatively and qualitatively, and concluded that the errors were not considered to be material to any previously-issued quarterly or annual financial statements. However, the Company concluded that it would revise the applicable prior period amounts in this filing to reflect the impact of these corrections because the cumulative amount of such corrections is expected to be material to the year ending December 31, 2015. The Company's prior-period financial statements will reflect these revisions for the applicable periods presented in future filings.

The table below presents the impact of these revisions, including the related tax effect, on the Company's previously-filed financial statements.



	December 31, 2014
	As Previously Reported			Adjustments			As Revised
Balance Sheet Data:
Deferred tax assets (noncurrent)	$	266,869		$	22,152		$	289,021
Total assets	3,871,827			22,152			3,893,979
Additional paid-in capital	2,404,118			60,890			2,465,008
Retained earnings	255,382			(38,738		)	216,644
Total stockholders' equity	2,542,325			22,152			2,564,477
Total liabilities and stockholders' equity	3,871,827			22,152			3,893,979

	Three Months Ended March 31, 2014
	As Previously Reported			Adjustments			As Revised
Consolidated Statement of Operations Data:
Selling, general, and administrative	$	108,850		$	(5,623	)	$	103,227
Total operating expenses	439,801			(5,623		)	434,178
Income from operations	185,939			5,623			191,562
Income before income taxes	175,263			5,623			180,886
Income tax expense	109,820			2,761			112,581
Net income	65,443			2,862			68,305
Net income per share - basic	$	0.66		$	0.03		$	0.69
Net income per share - diluted	$	0.58		$	0.03		$	0.61

Consolidated Statement of Cash Flows Data:
Cash flows from operating activities
Net income	$	65,443		$	2,862		$	68,305
Non-cash compensation expense	81,408			(5,623		)	75,785
Deferred taxes	(8,522		)	2,761			(5,761		)

The tables below present the impact of these revisions, including the related tax effects, on additional previously-filed interim and year-end Consolidated Statements of Operations (i) for the three and six months ended June 30, 2014, (ii) for the three and nine months ended September 30, 2014, and (iii) for the three months and year ended December 31, 2014.



	Three Months Ended June 30, 2014							Six Months Ended June 30, 2014
	As Previously Reported		Adjustments			As Revised		As Previously Reported		Adjustments			As Revised
Selling, general, and administrative	$	102,414	$	(5,684	)	$	96,730	$	211,264	$	(11,307	)	$	199,957
Total operating expenses	443,294		(5,684		)	437,610		883,095		(11,307		)	871,788
Income from operations	222,406		5,684			228,090		408,345		11,307			419,652
Income before income taxes	203,119		5,684			208,803		378,382		11,307			389,689
Income tax expense	110,384		2,068			112,452		220,204		4,829			225,033
Net income	92,735		3,616			96,351		158,178		6,478			164,656
Net income per share - basic	$	0.92	$	0.04		$	0.96	$	1.58	$	0.07		$	1.65
Net income per share - diluted	$	0.82	$	0.03		$	0.85	$	1.40	$	0.06		$	1.46



	Three Months Ended September 30, 2014							Nine Months Ended September 30, 2014
	As Previously Reported		Adjustments			As Revised		As Previously Reported		Adjustments			As Revised
Selling, general, and administrative	$	149,748	$	(5,745	)	$	144,003	$	361,012	$	(17,052	)	$	343,960
Total operating expenses	543,069		(5,745		)	537,324		1,426,164		(17,052		)	1,409,112
Income from operations	182,719		5,745			188,464		591,064		17,052			608,116
Income before income taxes	176,078		5,745			181,823		554,460		17,052			571,512
Income tax expense	96,358		2,090			98,448		316,562		6,919			323,481
Net income	79,720		3,655			83,375		237,898		10,133			248,031
Net income per share - basic	$	0.79	$	0.04		$	0.83	$	2.37	$	0.10		$	2.47
Net income per share - diluted	$	0.70	$	0.03		$	0.73	$	2.10	$	0.09		$	2.19



	Three Months Ended December 31, 2014							Year Ended December 31, 2014
	As Previously Reported		Adjustments			As Revised		As Previously Reported		Adjustments			As Revised
Selling, general, and administrative	$	143,743	$	31,564		$	175,307	$	504,755	$	14,512		$	519,267
Total operating expenses	554,962		31,564			586,526		1,981,126		14,512			1,995,638
Income from operations	247,367		(31,564		)	215,803		838,431		(14,512		)	823,919
Income before income taxes	221,287		(31,564		)	189,723		775,747		(14,512		)	761,235
Income tax expense	111,111		(11,483		)	99,628		427,673		(4,564		)	423,109
Net income	110,176		(20,081		)	90,095		348,074		(9,948		)	338,126
Net income per share - basic	$	1.09	$	(0.20	)	$	0.89	$	3.46	$	(0.10	)	$	3.36
Net income per share - diluted	$	0.96	$	(0.18	)	$	0.78	$	3.07	$	(0.09	)	$	2.98

Net Income Per Share (Notes)

3 Months Ended

Mar. 31, 2015

Earnings Per Share [Abstract]

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:



	Three Months Ended March 31,
	2015		2014
Net income - basic and diluted	$	76,021	$	68,305

(Shares in thousands)
Weighted average shares - basic	102,227		98,709
Effect of dilutive securities:
Stock options	9,313		9,879
Restricted stock	467		401
Warrants	2,512		3,162
Dilutive potential shares	12,292		13,442
Weighted average shares - diluted	114,519		112,151

Net income per share - basic	$	0.74	$	0.69
Net income per share - diluted	$	0.66	$	0.61

Shares which have been excluded from diluted per share amounts because their effect would have been antidilutive include the following:

Marketable Securities (Notes)

3 Months Ended

Mar. 31, 2015

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable securities as of March 31, 2015 and December 31, 2014 consist of both debt securities issued by investment grade institutions as well as equity securities. The Company also held restricted marketable securities as of December 31, 2014, consisting of the Company's investment in Avalanche Biotechnologies, Inc. common shares, which were subject to customary transfer restrictions until January 2015 under a lock-up agreement with the underwriters of Avalanche's initial public offering.

The following tables summarize the Company's investments in marketable securities:



	Amortized		Unrealized					Fair
As of March 31, 2015	Cost Basis		Gains		Losses			Value
Unrestricted
Corporate bonds	$	530,693	$	898	$	(99	)	$	531,492
U.S. government and government agency obligations	56,433		201		—			56,634
Municipal bonds	39,807		52		(3		)	39,856
Equity securities	17,005		72,575		—			89,580
	$	643,938	$	73,726	$	(102	)	$	717,562

As of December 31, 2014
Unrestricted
Corporate bonds	$	548,832	$	136	$	(1,462	)	$	547,506
U.S. government and government agency obligations	28,596		3		(46		)	28,553
Municipal bonds	37,044		37		(43		)	37,038
Equity securities	2,005		5,374		—			7,379
	616,477		5,550		(1,551		)	620,476
Restricted
Equity securities	15,000		76,439		—			91,439
	$	631,477	$	81,989	$	(1,551	)	$	711,915

The Company classifies its debt security investments based on their contractual maturity dates. The debt securities listed as of March 31, 2015 mature at various dates through August 2024. The fair values of debt security investments by contractual maturity consist of the following:



	March 31, 2015		December 31, 2014
Maturities within one year	$	234,257	$	251,761
Maturities after one year through five years	392,624		360,208
Maturities after five years through ten years	1,101		1,128
	$	627,982	$	613,097

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 March 31, 2015	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
Corporate bonds	$	136,720	$	(85	)	$	4,139	$	(14	)	$	140,859	$	(99	)
Municipal bonds	3,938		(3		)	—		—			3,938		(3		)
	$	140,658	$	(88	)	$	4,139	$	(14	)	$	144,797	$	(102	)

As of December 31, 2014
Corporate bonds	$	390,613	$	(1,462	)	—		—			$	390,613	$	(1,462	)
U.S. government and government agency obligations	25,549		(46		)	—		—			25,549		(46		)
Municipal bonds	10,779		(43		)	—		—			10,779		(43		)
	$	426,941	$	(1,551	)	—		—			$	426,941	$	(1,551	)

For the three months ended March 31, 2015 and 2014, total realized gains and losses on sales of marketable securities were not material.

Changes in the Company's accumulated other comprehensive income (loss) for the three months ended March 31, 2015 and 2014 related to unrealized gains and losses on available-for-sale marketable securities. For the three months ended March 31, 2015 and 2014, amounts reclassified from accumulated other comprehensive income (loss) into investment income in the Company's Statements of Operations were related to realized gains and losses on sales of marketable securities.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Fair Value Measurements (Notes)

3 Months Ended

Mar. 31, 2015

Fair Value Disclosures [Abstract]

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 March 31, 2015	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Available-for-sale marketable securities:
Unrestricted
Corporate bonds	$	531,492	—		$	531,492
U.S. government and government agency obligations	56,634		—		56,634
Municipal bonds	39,856		—		39,856
Equity securities	89,580		$	89,580	—
	$	717,562	$	89,580	$	627,982

As of December 31, 2014
Available-for-sale marketable securities:
Unrestricted
Corporate bonds	$	547,506	—		$	547,506
U.S. government and government agency obligations	28,553		—		28,553
Municipal bonds	37,038		—		37,038
Equity securities	7,379		$	7,379	—
	620,476		7,379		613,097
Restricted
Equity securities	91,439		—		91,439
	$	711,915	$	7,379	$	704,536

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 not record any charges for other-than-temporary impairment of its Level 2 marketable securities during the three months ended March 31, 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 three months ended March 31, 2015 and 2014.

During the three months ended March 31, 2015, transfers of marketable securities from Level 2 to Level 1 were $91.4 million in connection with the lapse of the transfer restrictions on the Company's investment in Avalanche common shares in January 2015. 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 three months ended March 31, 2015, and there were no transfers of marketable securities between Levels 1, 2, or 3 classifications during the three months ended March 31, 2014.

As of March 31, 2015 and December 31, 2014, the Company had $162.7 million and $169.4 million, respectively, in aggregate principal amount of 1.875% convertible senior notes (the "Notes") that will mature on October 1, 2016 unless earlier converted or repurchased. As described in Note 10, a portion of the Notes was surrendered for conversion during the first quarter of 2015. The fair value of the outstanding Notes was estimated to be $876.0 million and $819.8 million as of March 31, 2015 and December 31, 2014, respectively, and was determined based on Level 2 inputs, such as market and observable sources.

Additionally, as described in Note 10, pursuant to a November 2014 amendment agreement with a warrant holder, a portion of the Company's warrants were classified as a liability and measured at fair value as of December 31, 2014. The fair value of this liability was estimated to be $87.5 million as of December 31, 2014, and was determined based on Level 2 inputs, such as market and observable sources. During the first quarter of 2015, upon expiration of the November 2014 amendment agreement, the remaining warrants were re-measured at fair value and reclassified back to additional paid-in capital.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Inventory (Notes)

3 Months Ended

Mar. 31, 2015

Inventory Disclosure [Abstract]

Inventory

Inventories

Inventories consist of the following:



	March 31,		December 31,
	2015		2014
Raw materials	$	9,644	$	10,923
Work-in-process	83,990		73,519
Finished goods	11,398		10,768
Deferred costs	28,831		33,651
	$	133,863	$	128,861

Deferred costs represent the costs of product manufactured and shipped to the Company's collaborators for which recognition of revenue has been deferred.

Accounts Payable and Accrued Expenses (Notes)

3 Months Ended

Mar. 31, 2015

Payables and Accruals [Abstract]

Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses consist of the following:



	March 31,		December 31,
	2015		2014
Accounts payable	$	90,601	$	99,508
Accrued payroll and related costs	64,112		92,778
Accrued clinical trial expense	44,659		41,555
Accrued sales-related charges, deductions, and royalties	165,511		133,085
Other accrued expenses and liabilities	97,879		116,563
	$	462,762	$	483,489

Debt (Notes)	3 Months Ended
Debt (Notes)	Mar. 31, 2015
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	Debt a. Convertible Debt In the first quarter of 2015, the Company settled conversion obligations for $16.7 million principal amount of the Company's original $400.0 million aggregate principal amount of 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 the first quarter of 2015, the Company (i) paid $16.7 million in cash, (ii) issued 146,253 shares of Common Stock, and (iii) allocated $62.6 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 stockholder's equity. In addition, the Company recognized a $0.9 million loss on the debt extinguishment in connection with the Notes that were surrendered for conversion during the first quarter of 2015. In connection with the initial offering of the Notes in October 2011, the Company entered into convertible note hedge and warrant transactions with multiple counterparties, which were recorded to additional paid-in capital. As a result of the Note conversions described above, in the first quarter of 2015, the Company also exercised a proportionate amount of its convertible note hedges, for which the Company received 146,248 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 $12.3 million, as Treasury Stock during the first quarter of 2015. In addition to the Note conversions described above, the Company received notification in April 2015 that an additional $127.3 million principal amount of the Notes were surrendered for conversion, and settlement is anticipated during the second quarter of 2015. The Company has elected to settle the related conversion obligations through a combination of cash and shares (total payment will be based on the average of the volume-weighted-average prices of the Common Stock during the 40 trading-day cash settlement averaging period specified in the indenture governing the Notes). In connection with these Note conversions, the Company exercised a proportionate amount of its convertible note hedges, for which the Company expects to receive shares of Common Stock equivalent to the number of shares the Company will be required to issue to settle the non-cash portion of the related Note conversions. 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 by up to a maximum of 493,229. The reduction in the number of warrants was determined based on the number of warrants with respect to which the warrant holder had closed out its hedge position, provided that the warrant holder did not effect any purchases at a price per share exceeding $397.75 per share, during the period starting on November 26, 2014 and ending no later than February 12, 2015. 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 in connection with the warrant holder reducing the number of warrants it held. 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, 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. Additionally, in February 2015, the Company entered into another amendment agreement with the same warrant holder whereby the parties agreed to further reduce a portion of the number of warrants held by the warrant holder by up to a maximum of 76,749, for an aggregate amount payable by the Company not to exceed $24.0 million. The reduction in the number of warrants will be determined based on the number of warrants with respect to which the warrant holder has closed out its hedge position, provided that the warrant holder does not effect any purchases at a price per share exceeding $408.00 per share, during the period starting on March 2, 2015 and ending no later than May 7, 2015. The Company may settle, at its option, any payments due under the amendment agreement in cash or by delivering shares of Common Stock within three days following the warrant holder closing out its hedge position. Therefore, any payments made under the amendment agreement will be recorded to additional paid-in capital, consistent with the original accounting for the warrants under the 2011 issuance. During the first quarter of 2015, the reduction in the number of warrants in accordance with the February 2015 amended agreement was not material. 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 March 31, 2015. 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 March 31, 2015.

Income Taxes (Notes)	3 Months Ended
Income Taxes (Notes)	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is subject to U.S. federal, state, and foreign income taxes. The Company recorded an income tax provision in its Statement of Operations of $200.5 million and $112.6 million for the three months ended March 31, 2015 and 2014, respectively. The Company's effective tax rate was 72.5% and 62.2% for the three months ended March 31, 2015 and 2014, respectively. The Company's effective tax rate for the three months ended March 31, 2015 was negatively impacted by (i) losses incurred in foreign jurisdictions with rates lower than the federal statutory rate, (ii) the non-deductible Branded Prescription Drug Fee, and (iii) expiration, at the end of 2014, of the federal tax credit for increased research activities. The Company's effective tax rate for the three months ended March 31, 2014 was negatively impacted by (i) expiration at the end of 2013 of the federal tax credit for increased research activities, (ii) losses incurred in foreign jurisdictions with rates lower than the federal statutory rate, and (iii) New York state tax legislation enacted in the first quarter of 2014. This tax legislation reduced the New York state income tax rate to zero percent for "qualified manufacturers," including Regeneron, effective in 2014; however, it also resulted in the Company reducing its related deferred tax assets as a discrete item in the first quarter of 2014. As a result, this tax legislation caused a net increase in the Company's effective tax rate by 10.4% for the first quarter of 2014. The Company also recorded an income tax benefit in its Statement of Comprehensive Income of $2.5 million for the three months ended March 31, 2015, in connection with unrealized gains (losses) on available-for-sale marketable securities. For the three months ended March 31, 2014, no such income tax provision or benefit was required.

Statement of Cash Flows (Notes)	3 Months Ended
Statement of Cash Flows (Notes)	Mar. 31, 2015
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 March 31, 2015 and December 31, 2014 were $84.1 million and $56.2 million, respectively, of accrued capital expenditures. Included in accounts payable and accrued expenses as of March 31, 2014 and December 31, 2013 were $17.6 million and $16.1 million, respectively, of accrued capital expenditures Included in accounts payable and accrued expenses as of December 31, 2014 was $7.5 million for the Company's conversion settlement obligation related to the Company's convertible senior notes. No such amounts were payable as of March 31, 2014 and December 31, 2013, and the amount of such conversion settlement obligation was not material as of March 31, 2015. 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. 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 10. There were no such liabilities recorded in connection with warrants as of March 31, 2015, March 31, 2014, and December 31, 2013. The Company recognized a facility lease obligation of $10.8 million and $19.4 million during the three months ended March 31, 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. Subsequent event In April 2015, the Company acquired an approximate 100-acre parcel of undeveloped land adjacent to its current Tarrytown, New York location for an aggregate purchase price of $73.0 million. The Company intends to develop this property to accommodate and support its growth, primarily in connection with expanding its existing research and development and office space.

Legal Matters (Notes)	3 Months Ended
Legal Matters (Notes)	Mar. 31, 2015
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. Proceedings Relating to '287 Patent and '018 Patent The Company is a party to patent infringement litigation involving its European Patent No. 1,360,287 (the "'287 Patent") and its U.S. Patent No. 8,502,018 (the "'018 Patent"), both of which concern genetically altered 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 "'287 Patent Infringement Litigation" and "'018 Patent Infringement Litigation," respectively), the Company claims infringement of several claims of the '287 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 and the '018 Patent (as applicable). At this time the Company is not able to predict the outcome of, or an estimate of gain, if any, related to, these proceedings. Proceedings Relating to PCSK9 Antibody (Praluent) On October 17, 2014 and October 28, 2014, Amgen Inc. filed complaints against Regeneron, Sanofi, Aventisub LLC (subsequently removed and replaced with Sanofi-Aventis U.S. LLC), and Aventis Pharmaceuticals, Inc. in the United States District Court for the District of Delaware seeking an injunction to prohibit Regeneron and the other defendants from manufacturing, using, offering to sell, or selling within the United States (as well as importing into the United States) Praluent, the antibody to PCSK9 for LDL cholesterol reduction Regeneron is jointly developing with Sanofi. On November 11, 2014 and November 17, 2014 Amgen filed complaints against Regeneron, Sanofi, Sanofi-Aventis U.S. LLC, and Aventis Pharmaceuticals, Inc. in the same court seeking the same relief. Amgen asserts U.S. Patent Nos. 8,563,698, 8,829,165, and 8,859,741 in the first complaint, U.S. Patent Nos. 8,871,913 and 8,871,914 in the second complaint, U.S. Patent No. 8,883,983 in the third complaint, and U.S. Patent No. 8,889,834 in the fourth complaint. 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. On December 15, 2014, all of the four proceedings were consolidated into a single case. This matter has not yet progressed sufficiently through discovery and/or development of important factual information and legal issues to enable the Company to estimate a range of possible loss, if any.

Recently Issued Accounting Standards (Notes)	3 Months Ended
Recently Issued Accounting Standards (Notes)	Mar. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Description of New Accounting Pronouncements Not yet Adopted [Text Block]	Recently Issued Accounting Standards In May 2014, the FASB issued a new standard related to revenue recognition, 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. The new standard will be effective for annual and interim reporting periods beginning after December 15, 2016, and early adoption is not permitted. 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 and is evaluating the impact that this guidance will have on the Company's financial statements.

Net Product Sales (Policies)	3 Months Ended
Net Product Sales (Policies)	Mar. 31, 2015
Revenues [Abstract]
Revenue Recognition, Revenue Reductions [Policy Text Block]	Revenue from product sales is recorded net of applicable provisions for rebates and chargebacks under governmental programs, distribution-related fees, and other sales-related deductions.

Fair Value Measurements (Policies)	3 Months Ended
Fair Value Measurements (Policies)	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Transfer, Policy [Policy Text Block]	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.

Legal Matters (Policies)	3 Months Ended
Legal Matters (Policies)	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Legal Costs, Policy [Policy Text Block]	Costs associated with the Company's involvement in legal proceedings are expensed as incurred.

Net Product Sales (Tables)

3 Months Ended

Mar. 31, 2015

Revenues [Abstract]

Sales Related Deductions Activity

The following table summarizes the provisions, and credits/payments, for these sales-related deductions during the three months ended March 31, 2015 and 2014.



	Rebates & Chargebacks			Distribution- Related Fees			Other Sales- Related Deductions			Total
Balance as of December 31, 2014	$	3,083		$	21,166		$	532		$	24,781
Provision related to current period sales	11,353			24,781			1,383			37,517
Credits/payments	(9,779		)	(13,036		)	(1,411		)	(24,226		)
Balance as of March 31, 2015	$	4,657		$	32,911		$	504		$	38,072

Balance as of December 31, 2013	$	4,400		$	19,663		$	538		$	24,601
Provision related to current period sales	6,886			16,858			448			24,192
Credits/payments	(6,664		)	(16,310		)	(454		)	(23,428		)
Balance as of March 31, 2014	$	4,622		$	20,211		$	532		$	25,365

Collaboration Agreements (Tables)

3 Months Ended

Mar. 31, 2015

Collaboration Agreement [Abstract]

Collaboration revenue with related party



	Three Months Ended March 31,
Sanofi Collaboration Revenue	2015			2014
ZALTRAP:
Regeneron's share of losses in connection with commercialization of ZALTRAP	—			$	(3,212	)
Reimbursement of Regeneron research and development expenses	$	686		1,092
Other	15,236			2,177
Total ZALTRAP	15,922			57
Antibody:
Reimbursement of Regeneron research and development expenses	168,820			126,822
Reimbursement of Regeneron commercialization-related expenses	8,458			—
Regeneron's share of losses in connection with commercialization of antibodies	(22,405		)	—
Other	2,561			3,629
Total Antibody	157,434			130,451
	$	173,356		$	130,508

Collaboration revenue

The collaboration revenue the Company earned from Bayer HealthCare is detailed below:



	Three Months Ended March 31,
Bayer HealthCare Collaboration Revenue	2015		2014
EYLEA:
Regeneron's net profit in connection with commercialization of EYLEA outside the United States	$	89,426	$	61,159
Sales milestones	15,000		30,000
Cost-sharing of Regeneron EYLEA development expenses	2,657		20,347
Other	12,912		10,932
Total EYLEA	119,995		122,438
PDGFR-beta antibody:
Cost-sharing of REGN2176-3 development expenses	1,254		513
Other	2,597		2,361
Total PDGFR-beta	3,851		2,874
Total Bayer HealthCare collaboration revenue	$	123,846	$	125,312

Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Error Corrections and Prior Period Adjustments [Table Text Block]



	Three Months Ended June 30, 2014							Six Months Ended June 30, 2014
	As Previously Reported		Adjustments			As Revised		As Previously Reported		Adjustments			As Revised
Selling, general, and administrative	$	102,414	$	(5,684	)	$	96,730	$	211,264	$	(11,307	)	$	199,957
Total operating expenses	443,294		(5,684		)	437,610		883,095		(11,307		)	871,788
Income from operations	222,406		5,684			228,090		408,345		11,307			419,652
Income before income taxes	203,119		5,684			208,803		378,382		11,307			389,689
Income tax expense	110,384		2,068			112,452		220,204		4,829			225,033
Net income	92,735		3,616			96,351		158,178		6,478			164,656
Net income per share - basic	$	0.92	$	0.04		$	0.96	$	1.58	$	0.07		$	1.65
Net income per share - diluted	$	0.82	$	0.03		$	0.85	$	1.40	$	0.06		$	1.46



	Three Months Ended September 30, 2014							Nine Months Ended September 30, 2014
	As Previously Reported		Adjustments			As Revised		As Previously Reported		Adjustments			As Revised
Selling, general, and administrative	$	149,748	$	(5,745	)	$	144,003	$	361,012	$	(17,052	)	$	343,960
Total operating expenses	543,069		(5,745		)	537,324		1,426,164		(17,052		)	1,409,112
Income from operations	182,719		5,745			188,464		591,064		17,052			608,116
Income before income taxes	176,078		5,745			181,823		554,460		17,052			571,512
Income tax expense	96,358		2,090			98,448		316,562		6,919			323,481
Net income	79,720		3,655			83,375		237,898		10,133			248,031
Net income per share - basic	$	0.79	$	0.04		$	0.83	$	2.37	$	0.10		$	2.47
Net income per share - diluted	$	0.70	$	0.03		$	0.73	$	2.10	$	0.09		$	2.19



	Three Months Ended December 31, 2014							Year Ended December 31, 2014
	As Previously Reported		Adjustments			As Revised		As Previously Reported		Adjustments			As Revised
Selling, general, and administrative	$	143,743	$	31,564		$	175,307	$	504,755	$	14,512		$	519,267
Total operating expenses	554,962		31,564			586,526		1,981,126		14,512			1,995,638
Income from operations	247,367		(31,564		)	215,803		838,431		(14,512		)	823,919
Income before income taxes	221,287		(31,564		)	189,723		775,747		(14,512		)	761,235
Income tax expense	111,111		(11,483		)	99,628		427,673		(4,564		)	423,109
Net income	110,176		(20,081		)	90,095		348,074		(9,948		)	338,126
Net income per share - basic	$	1.09	$	(0.20	)	$	0.89	$	3.46	$	(0.10	)	$	3.36
Net income per share - diluted	$	0.96	$	(0.18	)	$	0.78	$	3.07	$	(0.09	)	$	2.98

The table below presents the impact of these revisions, including the related tax effect, on the Company's previously-filed financial statements.



	December 31, 2014
	As Previously Reported			Adjustments			As Revised
Balance Sheet Data:
Deferred tax assets (noncurrent)	$	266,869		$	22,152		$	289,021
Total assets	3,871,827			22,152			3,893,979
Additional paid-in capital	2,404,118			60,890			2,465,008
Retained earnings	255,382			(38,738		)	216,644
Total stockholders' equity	2,542,325			22,152			2,564,477
Total liabilities and stockholders' equity	3,871,827			22,152			3,893,979

	Three Months Ended March 31, 2014
	As Previously Reported			Adjustments			As Revised
Consolidated Statement of Operations Data:
Selling, general, and administrative	$	108,850		$	(5,623	)	$	103,227
Total operating expenses	439,801			(5,623		)	434,178
Income from operations	185,939			5,623			191,562
Income before income taxes	175,263			5,623			180,886
Income tax expense	109,820			2,761			112,581
Net income	65,443			2,862			68,305
Net income per share - basic	$	0.66		$	0.03		$	0.69
Net income per share - diluted	$	0.58		$	0.03		$	0.61

Consolidated Statement of Cash Flows Data:
Cash flows from operating activities
Net income	$	65,443		$	2,862		$	68,305
Non-cash compensation expense	81,408			(5,623		)	75,785
Deferred taxes	(8,522		)	2,761			(5,761		)

Net Income Per Share (Tables)

3 Months Ended

Mar. 31, 2015

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:



	Three Months Ended March 31,
	2015		2014
Net income - basic and diluted	$	76,021	$	68,305

(Shares in thousands)
Weighted average shares - basic	102,227		98,709
Effect of dilutive securities:
Stock options	9,313		9,879
Restricted stock	467		401
Warrants	2,512		3,162
Dilutive potential shares	12,292		13,442
Weighted average shares - diluted	114,519		112,151

Net income per share - basic	$	0.74	$	0.69
Net income per share - diluted	$	0.66	$	0.61

Antidilutive Securities

Shares which have been excluded from diluted per share amounts because their effect would have been antidilutive include the following:

Marketable Securities (Tables)

3 Months Ended

Mar. 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 March 31, 2015	Cost Basis		Gains		Losses			Value
Unrestricted
Corporate bonds	$	530,693	$	898	$	(99	)	$	531,492
U.S. government and government agency obligations	56,433		201		—			56,634
Municipal bonds	39,807		52		(3		)	39,856
Equity securities	17,005		72,575		—			89,580
	$	643,938	$	73,726	$	(102	)	$	717,562

As of December 31, 2014
Unrestricted
Corporate bonds	$	548,832	$	136	$	(1,462	)	$	547,506
U.S. government and government agency obligations	28,596		3		(46		)	28,553
Municipal bonds	37,044		37		(43		)	37,038
Equity securities	2,005		5,374		—			7,379
	616,477		5,550		(1,551		)	620,476
Restricted
Equity securities	15,000		76,439		—			91,439
	$	631,477	$	81,989	$	(1,551	)	$	711,915

Marketable Securities, Based on Contractual Maturity Dates

The fair values of debt security investments by contractual maturity consist of the following:



	March 31, 2015		December 31, 2014
Maturities within one year	$	234,257	$	251,761
Maturities after one year through five years	392,624		360,208
Maturities after five years through ten years	1,101		1,128
	$	627,982	$	613,097

Fair Value and Unrealized Losses of Marketable Securities



	Less than 12 Months					12 Months or Greater					Total
As of March 31, 2015	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
Corporate bonds	$	136,720	$	(85	)	$	4,139	$	(14	)	$	140,859	$	(99	)
Municipal bonds	3,938		(3		)	—		—			3,938		(3		)
	$	140,658	$	(88	)	$	4,139	$	(14	)	$	144,797	$	(102	)

As of December 31, 2014
Corporate bonds	$	390,613	$	(1,462	)	—		—			$	390,613	$	(1,462	)
U.S. government and government agency obligations	25,549		(46		)	—		—			25,549		(46		)
Municipal bonds	10,779		(43		)	—		—			10,779		(43		)
	$	426,941	$	(1,551	)	—		—			$	426,941	$	(1,551	)

- Definition

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

+ References + Details

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2015

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 March 31, 2015	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
Available-for-sale marketable securities:
Unrestricted
Corporate bonds	$	531,492	—		$	531,492
U.S. government and government agency obligations	56,634		—		56,634
Municipal bonds	39,856		—		39,856
Equity securities	89,580		$	89,580	—
	$	717,562	$	89,580	$	627,982

As of December 31, 2014
Available-for-sale marketable securities:
Unrestricted
Corporate bonds	$	547,506	—		$	547,506
U.S. government and government agency obligations	28,553		—		28,553
Municipal bonds	37,038		—		37,038
Equity securities	7,379		$	7,379	—
	620,476		7,379		613,097
Restricted
Equity securities	91,439		—		91,439
	$	711,915	$	7,379	$	704,536

Inventory (Tables)

3 Months Ended

Mar. 31, 2015

Inventory Disclosure [Abstract]

Schedule of Inventory, Current

Inventories consist of the following:



	March 31,		December 31,
	2015		2014
Raw materials	$	9,644	$	10,923
Work-in-process	83,990		73,519
Finished goods	11,398		10,768
Deferred costs	28,831		33,651
	$	133,863	$	128,861

Accounts Payable and Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2015

Payables and Accruals [Abstract]

Schedule of Accounts Payable and Accrued Liabilities

Accounts payable and accrued expenses consist of the following:



	March 31,		December 31,
	2015		2014
Accounts payable	$	90,601	$	99,508
Accrued payroll and related costs	64,112		92,778
Accrued clinical trial expense	44,659		41,555
Accrued sales-related charges, deductions, and royalties	165,511		133,085
Other accrued expenses and liabilities	97,879		116,563
	$	462,762	$	483,489

Net Product Sales (Details) - USD ($) $ in Thousands	3 Months Ended
Net Product Sales (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Revenue Disclosure [Line Items]
Net product sales	$ 544,573	$ 362,378
Activity of Sales Related Deductions [Roll Forward]
Balance	38,072	25,365	$ 24,781	$ 24,601
Provision related to current period sales	37,517	24,192
Credits/payments	(24,226)	(23,428)
Rebates and Chargebacks
Activity of Sales Related Deductions [Roll Forward]
Balance	4,657	4,622	3,083	4,400
Provision related to current period sales	11,353	6,886
Credits/payments	(9,779)	(6,664)
Distribution Related Fees
Activity of Sales Related Deductions [Roll Forward]
Balance	32,911	20,211	21,166	19,663
Provision related to current period sales	24,781	16,858
Credits/payments	(13,036)	(16,310)
Other Sales Related Deductions
Activity of Sales Related Deductions [Roll Forward]
Balance	504	532	$ 532	$ 538
Provision related to current period sales	1,383	448
Credits/payments	$ (1,411)	$ (454)
Customer concentration risk \| Gross Sales Revenue
Risks and Uncertainties [Abstract]
Concentration risk, percentage	69.00%	79.00%
EYLEA
Revenue Disclosure [Line Items]
Net product sales	$ 541,100	$ 359,000
ARCALYST
Revenue Disclosure [Line Items]
Net product sales	$ 3,500	$ 3,400

Collaboration Agreements (Sanofi) (Details) $ in Thousands	3 Months Ended
Collaboration Agreements (Sanofi) (Details) $ in Thousands	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2013 USD ($)
Collaboration Agreement [Line Items]
Number of sales milestone payments the Company received	1	2
Licenses Revenue	$ 27,837	$ 7,542
Research and development	343,113	287,379
Revenue from Related Parties	$ 173,356	130,508
ZALTRAP Agreement
Collaboration Agreement [Line Items]
Percentage of repayment of development balance out of profits	50.00%
Deferred Revenue, Revenue Recognized	$ 14,900
Licenses Revenue	19,800
Net profit (loss) from commercialization of products under collaboration agreement	0	(3,212)
Reimbursement of Regeneron research and development expenses	686	1,092
Contracts Revenue	15,236	2,177
Revenue from Related Parties	15,922	57
Antibody Collaboration
Collaboration Agreement [Line Items]
Net profit (loss) from commercialization of products under collaboration agreement	(22,405)	0
Recognition of Deferred Revenue	$ 2,561	3,629
Percentage of Trial Costs borne by collaborating party	80.00%
Percentage of Trial Costs borne by entity	20.00%
Research and development	$ 25,000	23,800
Reimbursement of Regeneron research and development expenses	168,820	126,822
Contracts Revenue	8,458	0
Revenue from Related Parties	$ 157,434	$ 130,451
PDGF
Collaboration Agreement [Line Items]
Number of Payments the Company made		2
Other Research and Development Expense		$ 5,000
Milestone payment			$ 30,000
Minimum [Member]
Collaboration Agreement [Line Items]
Percentage of net sales paid by the related party	15.00%
Maximum [Member]
Collaboration Agreement [Line Items]
Percentage of net sales paid by the related party	30.00%

Collaboration Agreements (Bayer HealthCare LLC) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)
Collaboration Agreement [Line Items]
Number of sales milestone payments the Company received	1	2
Other Collaboration Revenue	$ 123,846	$ 125,312
EYLEA
Collaboration Agreement [Line Items]
Net profit (loss) from commercialization of products under collaboration agreement	89,426	61,159
Revenue Recognition, Milestone Method, Revenue Recognized	15,000	30,000
Reimbursement of Regeneron research and development expenses	2,657	20,347
Contracts Revenue	12,912	10,932
Other Collaboration Revenue	119,995	122,438
PDGFR-beta
Collaboration Agreement [Line Items]
Reimbursement of Regeneron research and development expenses	1,254	513
Contracts Revenue	2,597	2,361
Other Collaboration Revenue	$ 3,851	$ 2,874

Collaboration Agreements (EYLEA) (Details) $ in Thousands	3 Months Ended
Collaboration Agreements (EYLEA) (Details) $ in Thousands	Mar. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)
Collaboration Agreement [Line Items]
Number of sales milestone payments the Company received	1	2
Levels of twelve month sales at which sales milestone payments were received - 500 million		$ 500,000
Levels of twelve month sales at which sales milestone payments were received - 600 million		$ 600,000
Period for Achieving Sales Target for Milestone Payment, Rolling Basis	12 months	12 months
sales achievement - $500 million
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized		$ 15,000
sales achievement - $600 million
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized		15,000
sales achievement - $200 million
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized	$ 15,000
Collaboration Agreement with Bayer HealthCare LLC [Member]
Collaboration Agreement [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized	15,000	30,000
Starting specified levels of annual sales at which sales milestone payments maybe received -$200 million	200,000
Reimbursement of Regeneron research and development expenses	$ 2,657	20,347
BRVO
Collaboration Agreement [Line Items]
Reimbursement of Regeneron research and development expenses		$ 15,700

Collaboration Agreements (PDGFR-beta Antibody) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014 USD ($)
PDGF
Collaboration Agreement [Line Items]
Amount of non refundable payment received for collaboration agreement		$ 25.5
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		$ 2.5
PDGFR-beta outside the US [Member]
Collaboration Agreement [Line Items]
Proceeds from Collaborators		$ 25.5

Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended					6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2014	Sep. 30, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred tax assets (noncurrent)	$ 289,484	$ 289,021						$ 289,021
Total assets	4,198,573	3,893,979						3,893,979
Additional paid-in-capital	2,812,573	2,465,008						2,465,008
Retained earnings	292,665	216,644						216,644
Total stockholders' equity	2,971,430	2,564,477						2,564,477
Total liabilities and stockholders' equity	4,198,573	3,893,979						3,893,979
Selling, general, and administrative	158,991	175,307	$ 144,003	$ 96,730	$ 103,227	$ 199,957	$ 343,960	519,267
Total operating expenses	586,059	586,526	537,324	437,610	434,178	871,788	1,409,112	1,995,638
Income from operations	283,553	215,803	188,464	228,090	191,562	419,652	608,116	823,919
Income before income taxes	276,523	189,723	181,823	208,803	180,886	389,689	571,512	761,235
Income tax expense	200,502	99,628	98,448	112,452	112,581	225,033	323,481	423,109
Income tax expense					112,581
Net Income (Loss) Attributable to Parent	$ 76,021	$ 90,095	$ 83,375	$ 96,351	$ 68,305	$ 164,656	$ 248,031	$ 338,126
Net income per share - basic	$ 0.74	$ 0.89	$ 0.83	$ 0.96	$ 0.69	$ 1.65	$ 2.47	$ 3.36
Net income per share - diluted	$ 0.66	$ 0.78	$ 0.73	$ 0.85	$ 0.61	$ 1.46	$ 2.19	$ 2.98
Non-cash compensation expense	$ 103,759				$ 75,785
Deferred taxes					(5,761)
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities	$ (163,523)				(14,778)
Previously Reported
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred tax assets (noncurrent)		$ 266,869						$ 266,869
Total assets		3,871,827						3,871,827
Additional paid-in-capital		2,404,118						2,404,118
Retained earnings		255,382						255,382
Total stockholders' equity		2,542,325						2,542,325
Total liabilities and stockholders' equity		3,871,827						3,871,827
Selling, general, and administrative		143,743	$ 149,748	$ 102,414	108,850	$ 211,264	$ 361,012	504,755
Total operating expenses		554,962	543,069	443,294	439,801	883,095	1,426,164	1,981,126
Income from operations		247,367	182,719	222,406	185,939	408,345	591,064	838,431
Income before income taxes		221,287	176,078	203,119	175,263	378,382	554,460	775,747
Income tax expense		111,111	96,358	110,384		220,204	316,562	427,673
Income tax expense					109,820
Net Income (Loss) Attributable to Parent		$ 110,176	$ 79,720	$ 92,735	$ 65,443	$ 158,178	$ 237,898	$ 348,074
Net income per share - basic		$ 1.09	$ 0.79	$ 0.92	$ 0.66	$ 1.58	$ 2.37	$ 3.46
Net income per share - diluted		$ 0.96	$ 0.70	$ 0.82	$ 0.58	$ 1.40	$ 2.10	$ 3.07
Deferred taxes					$ (8,522)
Revision Adjustment
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred tax assets (noncurrent)		$ 22,152						$ 22,152
Total assets		22,152						22,152
Additional paid-in-capital		60,890						60,890
Retained earnings		(38,738)						(38,738)
Total stockholders' equity		22,152						22,152
Total liabilities and stockholders' equity		22,152						22,152
Selling, general, and administrative		31,564	$ (5,745)	$ (5,684)	(5,623)	$ (11,307)	$ (17,052)	14,512
Total operating expenses		31,564	(5,745)	(5,684)	(5,623)	(11,307)	(17,052)	14,512
Income from operations		(31,564)	5,745	5,684	5,623	11,307	17,052	(14,512)
Income before income taxes		(31,564)	5,745	5,684	5,623	11,307	17,052	(14,512)
Income tax expense		(11,483)	2,090	2,068		4,829	6,919	(4,564)
Income tax expense					2,761
Net Income (Loss) Attributable to Parent		$ (20,081)	$ 3,655	$ 3,616	$ 2,862	$ 6,478	$ 10,133	$ (9,948)
Net income per share - basic		$ (0.20)	$ 0.04	$ 0.04	$ 0.03	$ 0.07	$ 0.10	$ (0.10)
Net income per share - diluted		$ (0.18)	$ 0.03	$ 0.03	$ 0.03	$ 0.06	$ 0.09	$ (0.09)
Deferred taxes					$ 2,761

Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended					6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2014	Sep. 30, 2014	Dec. 31, 2014
Earnings Per Share [Abstract]
Net income	$ 76,021	$ 90,095	$ 83,375	$ 96,351	$ 68,305	$ 164,656	$ 248,031	$ 338,126
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average shares outstanding - basic	102,227				98,709
Effect of dilutive securities (in shares):
Stock options	9,313				9,879
Restricted stock	467				401
Warrants	2,512				3,162
Dilutive potential shares	12,292				13,442
Weighted average shares - diluted (in shares)	114,519				112,151
Earnings Per Share, Basic and Diluted [Abstract]
Net income per share - basic	$ 0.74	$ 0.89	$ 0.83	$ 0.96	$ 0.69	$ 1.65	$ 2.47	$ 3.36
Net income per share - diluted (in dollars per share)	$ 0.66	$ 0.78	$ 0.73	$ 0.85	$ 0.61	$ 1.46	$ 2.19	$ 2.98
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares	3,673				3,646
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares	1,929				4,761

Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	$ 643,938	$ 631,477
Unrealized Gains	73,726	81,989
Unrealized (Losses)	(102)	(1,551)
Total fair value of available-for-sale marketable securities	717,562	711,915
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Maturities within one year	234,257	251,761
Maturities after one year through five years	392,624	360,208
Maturities after five years through ten years	1,101	1,128
Total	627,982	613,097
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months	140,658	426,941
Fair Value - 12 Months or Greater	4,139	0
Fair Value - Total	144,797	426,941
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months	(88)	(1,551)
Unrealized Loss - 12 Months or Greater	(14)	0
Unrealized Loss - Total	(102)	(1,551)
U.S. government and government agency obligations
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months		25,549
Fair Value - 12 Months or Greater		0
Fair Value - Total		25,549
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months		(46)
Unrealized Loss - 12 Months or Greater		0
Unrealized Loss - Total		(46)
Corporate bonds
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months	136,720	390,613
Fair Value - 12 Months or Greater	4,139	0
Fair Value - Total	140,859	390,613
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months	(85)	(1,462)
Unrealized Loss - 12 Months or Greater	(14)	0
Unrealized Loss - Total	(99)	(1,462)
Municipal bonds
Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than 12 Months	3,938	10,779
Fair Value - 12 Months or Greater	0	0
Fair Value - Total	3,938	10,779
Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Unrealized Loss - Less than 12 months	(3)	(43)
Unrealized Loss - 12 Months or Greater	0	0
Unrealized Loss - Total	(3)	(43)
Unrestricted [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	643,938	616,477
Unrealized Gains	73,726	5,550
Unrealized (Losses)	(102)	(1,551)
Total fair value of available-for-sale marketable securities	717,562	620,476
Unrestricted [Member] \| U.S. government and government agency obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	56,433	28,596
Unrealized Gains	201	3
Unrealized (Losses)	0	(46)
Total fair value of available-for-sale marketable securities	56,634	28,553
Unrestricted [Member] \| Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	530,693	548,832
Unrealized Gains	898	136
Unrealized (Losses)	(99)	(1,462)
Total fair value of available-for-sale marketable securities	531,492	547,506
Unrestricted [Member] \| Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	39,807	37,044
Unrealized Gains	52	37
Unrealized (Losses)	(3)	(43)
Total fair value of available-for-sale marketable securities	39,856	37,038
Unrestricted [Member] \| Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis	17,005	2,005
Unrealized Gains	72,575	5,374
Unrealized (Losses)	0	0
Total fair value of available-for-sale marketable securities	$ 89,580	7,379
Restricted [Member] \| Equity Securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost Basis		15,000
Unrealized Gains		76,439
Unrealized (Losses)		0
Total fair value of available-for-sale marketable securities		$ 91,439

Fair Value Measurements (Details) - USD ($)	3 Months Ended
Fair Value Measurements (Details) - USD ($)	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	$ 91,400,000	$ 0
Available-for-sale marketable securities:
Total fair value of available-for-sale marketable securities	717,562,000		$ 711,915,000
Convertible senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Debt, Noncurrent	$ 162,700,000		$ 169,400,000
Convertible Debt [Abstract]
Interest rate, stated percentage	1.875%		1.875%
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
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable Securities, Unrealized Gain (Loss)	0	0
Measured on a recurring basis
Available-for-sale marketable securities:
Total fair value of available-for-sale marketable securities	717,562,000		$ 711,915,000
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	89,580,000		7,379,000
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	627,982,000		704,536,000
Convertible Debt [Abstract]
Fair value of the outstanding notes	876,000,000		819,800,000
Restricted [Member] \| Measured on a recurring basis
Available-for-sale marketable securities:
Equity securities			91,439,000
Restricted [Member] \| Measured on a recurring basis \| Significant Other Observable Inputs (Level 2)
Available-for-sale marketable securities:
Equity securities			91,439,000
Unrestricted [Member]
Available-for-sale marketable securities:
Total fair value of available-for-sale marketable securities	717,562,000		620,476,000
Unrestricted [Member] \| Measured on a recurring basis
Available-for-sale marketable securities:
U.S. government and government agency obligations	56,634,000		28,553,000
Corporate bonds	531,492,000		547,506,000
Municipal bonds	39,856,000		37,038,000
Equity securities	89,580,000		7,379,000
Total fair value of available-for-sale marketable securities			620,476,000
Unrestricted [Member] \| Measured on a recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Available-for-sale marketable securities:
Equity securities	89,580,000		7,379,000
Total fair value of available-for-sale marketable securities			7,379,000
Unrestricted [Member] \| Measured on a recurring basis \| Significant Other Observable Inputs (Level 2)
Available-for-sale marketable securities:
U.S. government and government agency obligations	56,634,000		28,553,000
Municipal bonds	39,856,000		37,038,000
Equity securities	531,492,000		547,506,000
Total fair value of available-for-sale marketable securities			613,097,000
Warrant Transactions [Member]
Convertible Debt [Abstract]
Other Liabilities, Fair Value Disclosure	$ 0	$ 0	$ 87,500,000	$ 0

Inventory (Schedule of Inventory) (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Raw materials	$ 9,644	$ 10,923
Work in process	83,990	73,519
Finished goods	11,398	10,768
Deferred costs	28,831	33,651
Total Inventories	$ 133,863	$ 128,861

Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2014
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accounts payable	$ 90,601	$ 99,508
Accrued payroll and related costs	64,112	92,778
Accrued clinical trial expense	44,659	41,555
Accrued sales-related charges, deductions and royalties	165,511	133,085
Other accrued expenses and liabilities	97,879	116,563
Accounts payable and accrued expenses	$ 462,762	$ 483,489

Debt (Details)	1 Months Ended			3 Months Ended
Debt (Details)	Apr. 30, 2015 USD ($)	Feb. 28, 2015 USD ($)	Nov. 30, 2014 $ / shares shares	Mar. 31, 2015 USD ($) $ / shares shares	Mar. 31, 2014 USD ($)	Dec. 31, 2014 USD ($) shares	Oct. 31, 2011 USD ($)
Debt Conversion				$ 16,700,000
Debt Instrument, Face Amount							$ 400,000,000
Repayments of Convertible Debt				$ 16,686,000	$ 0
Stock issued during period conversion of convertible notes \| shares				146,253
Gains (Losses) on Extinguishment of Debt				$ 942,000	0
Treasury Stock, Shares \| shares				2,163,980		2,017,732
Treasury Stock, Value				$ 181,817,000		$ 169,530,000
Maximum reduction of warrants held by warrant holder \| shares			493,229	76,749
Limit price per share for warrant holders to close out hedge position \| $ / shares			$ 397.75	$ 408.00
Payments for Repurchase of Warrants		$ 124,000,000		$ 124,531,000	$ 0
Maximum amount of warrant payable				24,000,000
Credit Facility [Domain]
Line of Credit Facility, Maximum Borrowing Capacity				$ 750,000,000
Line of Credit Facility, Expiration Period				5 years
Line of Credit Facility, Increase (Decrease), Net				$ 250,000,000
Line of Credit Facility, Maximum Month-end Outstanding Amount				100,000,000
Line of Credit Facility, Fair Value of Amount Outstanding				$ 0
Convertible senior notes
Treasury Stock, Shares \| shares				146,248
Treasury Stock, Value				$ 12,300,000
Trading days to calculate settlement				40
Additional Paid-in Capital [Member]
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments				$ 62,600,000
Adjustments to Additional Paid in Capital, Warrant Issued				$ 23,300,000
Scenario, Forecast [Member]
Debt Conversion	$ 127,300,000
Warrant Transactions [Member]
Accounts Payable, Other						$ 59,800,000
Reduction of number of warrants \| shares				416,480

Income Taxes (Details) - USD ($)	3 Months Ended					6 Months Ended	9 Months Ended	12 Months Ended
Income Taxes (Details) - USD ($)	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2014	Sep. 30, 2014	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Total income tax expense (benefit)	$ 200,502,000	$ 99,628,000	$ 98,448,000	$ 112,452,000	$ 112,581,000	$ 225,033,000	$ 323,481,000	$ 423,109,000
Effective income tax rate	72.50%				62.20%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent					0.00%
Effective Income Tax Rate Reconciliation, Change in Tax Rates, Percent					10.40%
Available-for-sale Securities, Income Tax Expense on Change in Unrealized Holding Gain (Loss)	$ 2,466,000				$ 0

Statement of Cash Flows (Details) - USD ($)	1 Months Ended	3 Months Ended
Statement of Cash Flows (Details) - USD ($)	Apr. 30, 2015	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Accrued capital expenditures		$ 84,100,000	$ 17,600,000	$ 56,200,000	$ 16,100,000
Notes Payable			0	7,500,000	0
Facility lease obligation recognized during the period		10,800,000	19,400,000
Warrant Transactions [Member]
Accounts Payable, Other				59,800,000
Other Liabilities, Fair Value Disclosure		$ 0	$ 0	$ 87,500,000	$ 0
Subsequent Event [Member]
Land	$ 73,000,000

Subsequent Events (Details) $ in Millions	1 Months Ended
Subsequent Events (Details) $ in Millions	Apr. 30, 2015 USD ($)
Subsequent Event [Member]
Subsequent Event [Line Items]
Payments to Acquire Land Held-for-use	$ 73.0