Document and Entity Information	6 Months Ended
Document and Entity Information	Jun. 30, 2015	Jul. 17, 2015 Common Stock	Jul. 17, 2015 Class A Stock
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	Jun. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		101,736,534	1,951,868

CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 390,554	$ 648,719
Marketable securities	213,694	251,761
Accounts receivable - trade, net	1,071,665	739,379
Accounts Receivable from Sanofi	197,693	111,510
Accounts receivable from Bayer HealthCare	125,767	125,483
Inventories	171,266	128,861
Deferred tax assets	69,603	46,179
Prepaid expenses and other current assets	43,099	79,046
Total current assets	2,283,341	2,130,938
Marketable securities	589,595	460,154
Property, plant, and equipment, at cost, net of accumulated depreciation and amortization	1,326,112	974,309
Deferred tax assets	323,784	269,237
Other assets	4,138	3,034
Total assets	4,526,970	3,837,672
Current liabilities:
Accounts payable and accrued expenses	529,505	483,489
Deferred revenue from Sanofi, current portion	18,026	15,927
Deferred revenue - other, current portion	51,720	58,098
Other Liabilities, Current	2,291	97,146
Total current liabilities	601,542	654,660
Deferred revenue from Sanofi	46,095	62,819
Deferred Revenue - other	76,748	72,430
Facility lease obligations	357,687	310,938
Convertible senior notes	30,360	146,773
Other long-term liabilities	76,080	39,801
Total liabilities	1,188,512	1,287,421
Stockholders' equity:
Preferred Stock	0	0
Additional paid-in capital	3,118,969	2,450,782
Retained earnings	487,308	216,644
Accumulated other comprehensive income	19,153	52,251
Treasury stock	(287,079)	(169,530)
Total stockholders' equity	3,338,458	2,550,251
Total liabilities and stockholders' equity	4,526,970	3,837,672
Class A Stock
Stockholders' equity:
Common stock	2	2
Common Stock
Stockholders' equity:
Common stock	$ 105	$ 102

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Jun. 30, 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)	3,416,788	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)	1,951,868	1,973,368
Common Stock, shares outstanding (in shares)	1,951,868	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)	320,000,000
Common Stock, shares issued (in shares)	105,106,034	102,475,154

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues:
Net product sales	$ 657,819	$ 418,022	$ 1,202,392	$ 780,400
Sanofi collaboration revenue	195,110	142,595	368,466	273,103
Bayer HealthCare collaboration revenue	134,237	97,295	258,083	222,607
Technology licensing and other revenue	11,451	7,788	39,288	15,330
Total revenues	998,617	665,700	1,868,229	1,291,440
Expenses:
Research and development	390,330	294,501	733,443	581,880
Selling, general, and administrative	174,588	96,730	333,579	199,957
Cost of goods sold	60,855	29,945	103,425	57,418
Cost of collaboration and contract manufacturing	27,985	16,434	69,370	32,533
Total expenses	653,758	437,610	1,239,817	871,788
Income from operations	344,859	228,090	628,412	419,652
Other income (expense):
Investment and other income	1,849	1,677	1,930	2,614
Interest expense	(2,748)	(10,177)	(8,917)	(21,790)
Loss on extinguishment of debt	(15,964)	(10,787)	(16,906)	(10,787)
Total other income (expense)	(16,863)	(19,287)	(23,893)	(29,963)
Income before income taxes	327,996	208,803	604,519	389,689
Income tax expense	(133,353)	(112,452)	(333,855)	(225,033)
Net income	194,643	96,351	270,664	164,656
Net income per share - basic	$ 1.89	$ 0.96	$ 2.64	$ 1.65
Net income per share - diluted	$ 1.69	$ 0.85	$ 2.35	$ 1.46
Weighted average shares outstanding - basic	102,886	100,391	102,558	100,085
Weighted average shares outstanding - diluted	115,259	113,032	114,962	113,121
Statements of Comprehensive Income
Net income	194,643	96,351	270,664	164,656
Other comprehensive (loss) income:
Unrealized (loss) gain on marketable securities, net of tax	(28,751)	2,798	(33,098)	5,451
Comprehensive income	$ 165,892	$ 99,149	$ 237,566	$ 170,107

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 270,664	$ 164,656
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization	31,325	24,546
Non-cash compensation expense	198,016	140,613
Non-cash interest expense	2,745	10,871
Losses on Extinguishment of Debt	16,906	10,787
Other non-cash charges and expenses, net	17,627	6,598
Deferred Taxes	(59,069)	(19,092)
Changes in assets and liabilites
Increase in Sanofi, Bayer HealthCare, and trade accounts receivable	(418,753)	84,776
Increase in Inventories	(49,852)	(37,295)
Decrease (increase) in prepaid expenses and other assets	33,842	(29,446)
(Decrease) increase in deferred revenue	(16,685)	16,105
Increase (decrease) in accounts payable, accrued expenses and other liabilities	129,338	16,820
Total adjustments	(114,560)	225,283
Net cash (used in) provided by operating activities	156,104	389,939
Cash flows from investing activities:
Purchases of marketable securities	(340,844)	(374,509)
Sales or maturities of marketable securities	193,769	155,850
Capital expenditures	(354,055)	(135,695)
Net cash used in investing activities	(501,130)	(354,354)
Cash flows from financing activities:
Proceeds (payments) in connection with facility and capital lease obligations	26,780	(534)
Repayments of convertible senior notes	(144,001)	(61,125)
Payments in connection with deduction of outstanding warrants	(124,531)	(143,041)
Proceeds from issuance of Common Stock	115,825	63,057
Payments in connection with Common Stock tendered for employee tax obligations	(35,930)	(64,990)
Excess tax benefit from stock-based compensation	248,718	235,575
Net cash provided by financing activities	86,861	28,942
Net decrease in cash and cash equivalents	(258,165)	64,527
Cash and cash equivalents at beginning of period	648,719	535,608
Cash and cash equivalents at end of period	$ 390,554	$ 600,135

Interim Financial Statements (Notes)	6 Months Ended
Interim Financial Statements (Notes)	Jun. 30, 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. 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 and six months ended June 30, 2014 and Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2014 contained in the Company's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 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. In addition, the previously issued Consolidated Balance Sheet as of December 31, 2014 has been revised in this Quarterly Report on Form 10-Q to reflect a correction related to the accounting for costs incurred in connection with commercial bulk drug product manufactured by the Company, but not billed, under the Company's collaboration agreements with Sanofi and Bayer HealthCare, and the related tax impacts. The correcting adjustments results in a reduction to both accounts receivable and deferred revenue by $41.0 million, and reduce both income tax assets, net and additional paid-in capital by $14.2 million. The previously issued Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2014 was also revised in this Quarterly Report on Form 10-Q to reflect an $8.6 million increase in cash flows from operating activities and a corresponding reduction in cash flows from financing activities related to the tax impact of these adjustments. These adjustments had no impact on the Company's previously issued Consolidated Statements of Operations and Comprehensive Income in any reporting period. The Company determined that the error is not material to any previously-issued financial statements. Certain reclassifications have been made to prior period amounts to conform with the current period’s presentation.

Net Product Sales (Notes)

6 Months Ended

Jun. 30, 2015

Revenues [Abstract]

Product Sales and Concentration Risk [Text Block]

Product Sales

EYLEA^® net product sales in the United States totaled $654.6 million and $414.8 million for the three months ended June 30, 2015 and 2014, respectively, and $1,195.7 million and $773.8 million for the six months ended June 30, 2015 and 2014, respectively. In addition, ARCALYST^® net product sales totaled $3.2 million for each of the three-month periods ended June 30, 2015 and 2014, respectively, and $6.7 million and $6.6 million for the six months ended June 30, 2015 and 2014, respectively.

The Company recorded 69% and 73% for the three months ended June 30, 2015 and 2014, respectively, and 69% and 76% for the six months ended June 30, 2015 and 2014, 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 six months ended June 30, 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	25,481			54,747			3,454			83,682
Credits/payments	(23,090		)	(36,433		)	(3,482		)	(63,005		)
Balance as of June 30, 2015	$	5,474		$	39,480		$	504		$	45,458

Balance as of December 31, 2013	$	4,400		$	19,663		$	538		$	24,601
Provision related to current period sales	14,817			36,206			818			51,841
Credits/payments	(15,077		)	(35,449		)	(834		)	(51,360		)
Balance as of June 30, 2014	$	4,140		$	20,420		$	522		$	25,082

Collaboration Agreements (Notes)

6 Months Ended

Jun. 30, 2015

Collaboration Agreement [Abstract]

Collaboration Agreements

a. Sanofi

Sanofi collaboration revenue, as detailed below, consisted primarily of reimbursement for research and development expenses that the Company incurred, partly offset by sharing of pre-launch commercialization expenses, in connection with the companies' Discovery and Preclinical Development Agreement ("Antibody Discovery Agreement") and License and Collaboration Agreement (each as amended), collectively referred to as the "Antibody Collaboration".



	Three Months Ended June 30,
Sanofi Collaboration Revenue	2015			2014
Antibody:
Reimbursement of Regeneron research and development expenses	$	211,516		$	137,893
Reimbursement of Regeneron commercialization-related expenses	27,347			4,307
Regeneron's share of losses in connection with commercialization of antibodies	(46,313		)	(4,295		)
Other	2,560			2,560
Total Antibody	195,110			140,465
ZALTRAP:
Regeneron's share of losses in connection with commercialization of ZALTRAP	—			(692		)
Reimbursement of Regeneron research and development expenses	—			1,338
Other	—			1,484
Total ZALTRAP	—			2,130
	$	195,110		$	142,595



	Six Months Ended June 30,
Sanofi Collaboration Revenue	2015			2014
Antibody:
Reimbursement of Regeneron research and development expenses	$	380,336		$	264,715
Reimbursement of Regeneron commercialization-related expenses	35,805			5,375
Regeneron's share of losses in connection with commercialization of antibodies	(68,718		)	(4,295		)
Other	5,121			5,121
Total Antibody	352,544			270,916
ZALTRAP:
Regeneron's share of losses in connection with commercialization of ZALTRAP	—			(3,904		)
Reimbursement of Regeneron research and development expenses	686			2,430
Other	15,236			3,661
Total ZALTRAP	15,922			2,187
	$	368,466		$	273,103

Antibodies

Under the Company's November 2007 Antibody Collaboration with Sanofi, as amended, 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 June 30, 2015 and 2014, the Company recognized as additional research and development expense $22.5 million and $29.1 million, respectively, and during the six months ended June 30, 2015 and 2014, the Company recognized as additional research and development expense $47.5 million and $52.9 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’ License and Collaboration Agreement. In July 2015, the U.S. Food and Drug Administration ("FDA") approved Praluent for the treatment of adults with heterozygous familial hypercholesterolemia or clinical atherosclerotic cardiovascular disease, who require additional lowering of low-density lipoprotein ("LDL") cholesterol.

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 ophthalmology. With respect to PDGF antibodies, the Company made two $5.0 million development milestone payments to Sanofi in the first quarter of 2014 and a $10.0 million development milestone payment to Sanofi in the second quarter of 2015, each of which was recorded as research and development expense. The Company is also obligated to pay up to $20.0 million in additional potential development milestones as well as royalties on any future sales of PDGF antibodies.

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 will be reduced from $160.0 million to $145.0 million in 2015, and from $160.0 million 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 now be funded by Sanofi under the terms of the companies’ new immuno-oncology collaboration.

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 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. 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 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 three and six months ended June 30, 2015, the Company recorded $3.2 million and $23.0 million, respectively, 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.

Immuno-Oncology

In July 2015, the Company and Sanofi entered into a global strategic 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 will make a $265.0 million non-refundable upfront payment to the Company. Pursuant to the IO Discovery Agreement, the Company will spend up to $1,090.0 million 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, 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 Funding 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 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. With regard to product candidates for which proof-of-concept is established, Sanofi will have the option to license rights to the 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 will make a $375.0 million non-refundable upfront 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 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 any profits from worldwide sales of collaboration products. Regeneron 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.

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 June 30,
Bayer HealthCare Collaboration Revenue	2015		2014
EYLEA:
Regeneron's net profit in connection with commercialization of EYLEA outside the United States	$	106,631	$	66,781
Sales milestones	—		15,000
Cost-sharing of Regeneron EYLEA development expenses	2,464		1,494
Other	16,618		10,813
Total EYLEA	125,713		94,088
PDGFR-beta antibody:
Cost-sharing of REGN2176-3 development expenses	5,926		626
Other	2,598		2,581
Total PDGFR-beta	8,524		3,207
	$	134,237	$	97,295



	Six Months Ended June 30,
Bayer HealthCare Collaboration Revenue	2015		2014
EYLEA:
Regeneron's net profit in connection with commercialization of EYLEA outside the United States	$	196,057	$	127,940
Sales milestones	15,000		45,000
Cost-sharing of Regeneron EYLEA development expenses	5,121		21,841
Other	29,530		21,745
Total EYLEA	245,708		216,526
PDGFR-beta antibody:
Cost-sharing of REGN2176-3 development expenses	7,180		1,139
Other	5,195		4,942
Total PDGFR-beta	12,375		6,081
	$	258,083	$	222,607

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 half of 2014, the Company earned three $15.0 million sales milestones from Bayer HealthCare upon total aggregate net sales of EYLEA outside the United States exceeding $500 million, $600 million, and $700 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) and a $5.0 million development milestone payment to the Company in the second quarter of 2015 (which was recognized as a substantive milestone).

Stock-based Compensation (Notes)

6 Months Ended

Jun. 30, 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 applicable Long-Term Incentive Plan based on the grant-date fair value of those awards. The Company recognized stock-based compensation expense of $94.3 million and $64.8 million for the three months ended June 30, 2015 and 2014, respectively, and $198.0 million and $140.6 million for the six months ended June 30, 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 June 30, 2014							Six Months Ended June 30, 2014
	As Previously Reported		Adjustments			As Revised		As Previously Reported		Adjustments			As Revised
Consolidated Statement of Operations Data:
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



	Six Months Ended June 30, 2014
	As Previously Reported			Adjustments			As Revised
Consolidated Statement of Cash Flows Data:
Cash flows from operating activities
Net income	$	158,178		$	6,478		$	164,656
Non-cash compensation expense	151,920			(11,307		)	140,613
Deferred taxes	(32,543		)	4,829			(27,714		)

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 for the three and nine months ended September 30, 2014, and for the three months and year ended December 31, 2014.



	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)

6 Months Ended

Jun. 30, 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 June 30,
	2015		2014
Net income - basic and diluted	$	194,643	$	96,351

(Shares in thousands)
Weighted average shares - basic	102,886		100,391
Effect of dilutive securities:
Stock options	9,438		9,359
Restricted stock	474		405
Warrants	2,461		2,877
Dilutive potential shares	12,373		12,641
Weighted average shares - diluted	115,259		113,032

Net income per share - basic	$	1.89	$	0.96
Net income per share - diluted	$	1.69	$	0.85



	Six Months Ended June 30,
	2015		2014
Net income - basic and diluted	$	270,664	$	164,656

(Shares in thousands)
Weighted average shares - basic	102,558		100,085
Effect of dilutive securities:
Stock options	9,441		9,615
Restricted stock	471		403
Warrants	2,492		3,018
Dilutive potential shares	12,404		13,036
Weighted average shares - diluted	114,962		113,121

Net income per share - basic	$	2.64	$	1.65
Net income per share - diluted	$	2.35	$	1.46

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

Marketable Securities (Notes)

6 Months Ended

Jun. 30, 2015

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable securities as of June 30, 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 June 30, 2015	Cost Basis		Gains		Losses			Value
Unrestricted
Corporate bonds	$	661,084	$	256	$	(951	)	$	660,389
U.S. government and government agency obligations	56,998		31		(24		)	57,005
Municipal bonds	39,764		17		(10		)	39,771
Equity securities	17,005		29,119		—			46,124
	$	774,851	$	29,423	$	(985	)	$	803,289

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 June 30, 2015 mature at various dates through August 2024. The fair values of debt security investments by contractual maturity consist of the following:



	June 30, 2015		December 31, 2014
Maturities within one year	$	213,694	$	251,761
Maturities after one year through five years	542,369		360,208
Maturities after five years through ten years	1,102		1,128
	$	757,165	$	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 June 30, 2015	Fair Value		Unrealized Loss			Fair Value			Unrealized Loss			Fair Value		Unrealized Loss
Corporate bonds	$	413,794	$	(920	)	$	7,602		$	(31	)	$	421,396	$	(951	)
U.S. government and government agency obligations	20,397		(24		)	—			—			20,397		(24		)
Municipal bonds	12,675		(10		)	—		—	—			12,675		(10		)
	$	446,866	$	(954	)	$	7,602		$	(31	)	$	454,468	$	(985	)

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 and six months ended June 30, 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 and six months ended June 30, 2015 and 2014 related to unrealized gains and losses on available-for-sale marketable securities. For the three and six months ended June 30, 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.

Fair Value Measurements (Notes)

6 Months Ended

Jun. 30, 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 June 30, 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	$	660,389	—		$	660,389
U.S. government and government agency obligations	57,005		—		57,005
Municipal bonds	39,771		—		39,771
Equity securities	46,124		$	46,124	—
	$	803,289	$	46,124	$	757,165

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 and six months ended June 30, 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 and six months ended June 30, 2015 and 2014. During the six months ended June 30, 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 six months ended June 30, 2015, and there were no transfers of marketable securities between Levels 1, 2, or 3 classifications during the six months ended June 30, 2014.

As of June 30, 2015 and December 31, 2014, the Company had $33.3 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 half of 2015. The fair value of the outstanding Notes was estimated to be $201.6 million and $819.8 million as of June 30, 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

Three Months Ended June 30,

(Shares in thousands)

Stock options

Convertible senior notes