0001804220-20-000022 | 10-Q | XBRL Viewer | Regeneron Pharmaceuticals INC

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Cover - shares	6 Months Ended
Cover - shares	Jun. 30, 2020	Jul. 23, 2020
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	0-19034
Entity Registrant Name	REGENERON PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	NY
Entity Tax Identification Number	13-3444607
Entity Address, Address Line One	777 Old Saw Mill River Road
Entity Address, City or Town	Tarrytown
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10591-6707
City Area Code	914
Local Phone Number	847-7000
Title of 12(b) Security	Common Stock - par value $.001 per share
Trading Symbol	REGN
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0000872589
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Amendment Flag	false
Class A Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		1,848,970
Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		104,543,424

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 1,992.2	$ 1,617.8
Marketable securities	1,152.0	1,596.5
Accounts receivable - trade, net	1,991.0	2,100.0
Accounts receivable - Sanofi	389.2	260.6
Accounts receivable - other	431.1	425.0
Inventories	1,640.9	1,415.5
Prepaid expenses and other current assets	263.8	273.7
Total current assets	7,860.2	7,689.1
Marketable securities	2,587.6	3,256.8
Property, plant, and equipment, net	3,031.4	2,890.4
Deferred tax assets	774.0	824.2
Other noncurrent assets	175.5	144.7
Total assets	14,428.7	14,805.2
Current liabilities:
Accounts payable	380.1	418.1
Accrued expenses and other current liabilities	1,257.0	1,211.4
Debt	1,500.0	0.0
Other liabilities - Sanofi	103.8	85.0
Total current liabilities	3,702.4	2,096.6
Finance lease liabilities	715.9	713.9
Other noncurrent liabilities	457.9	317.7
Total liabilities	5,371.3	3,715.5
Stockholders' equity:
Preferred Stock, $.01 par value; 30,000,000 shares authorized; issued and outstanding - none	0.0	0.0
Additional paid-in capital	6,263.0	4,428.6
Retained earnings	8,901.7	7,379.8
Accumulated other comprehensive income	35.5	21.1
Treasury Stock, at cost; 15,578,240 shares in 2020 and 4,860,123 shares in 2019	(6,142.9)	(739.9)
Total stockholders' equity	9,057.4	11,089.7
Total liabilities and stockholders' equity	14,428.7	14,805.2
Class A Stock
Stockholders' equity:
Common stock	0.0	0.0
Total stockholders' equity	0.0	0.0
Common Stock
Stockholders' equity:
Common stock	0.1	0.1
Total stockholders' equity	0.1	0.1
Sanofi
Current liabilities:
Deferred revenue, current	380.2	310.5
Deferred revenue, noncurrent	37.8	27.7
Other noncurrent liabilities	390.3	482.0
Other
Current liabilities:
Deferred revenue, current	81.3	71.6
Deferred revenue, noncurrent	$ 67.0	$ 77.6

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Stockholders' Equity Attributable to Parent [Abstract]
Preferred Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred Stock, shares authorized (in shares)	30,000,000	30,000,000
Preferred Stock, shares issued (in shares)	0	0
Preferred Stock, shares outstanding (in shares)	0	0
Treasury Stock (in shares)	15,578,240	4,860,123
Class A Stock
Stockholders' Equity Attributable to Parent [Abstract]
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	40,000,000	40,000,000
Common Stock, shares issued (in shares)	1,848,970	1,848,970
Common Stock, shares outstanding (in shares)	1,848,970	1,848,970
Common Stock
Stockholders' Equity Attributable to Parent [Abstract]
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	320,000,000	320,000,000
Common Stock, shares issued (in shares)	119,757,931	113,288,103

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Revenues	$ 1,952.0	$ 1,577.8	$ 3,780.2	$ 2,950.4
Expenses:
Research and development	722.0	885.5	1,305.9	1,371.6
Selling, general, and administrative	348.3	294.6	715.6	585.7
Other operating (income) expense, net	(50.2)	(63.7)	(90.6)	(120.4)
Total expenses	1,295.6	1,262.2	2,423.7	2,154.8
Income from operations	656.4	315.6	1,356.5	795.6
Other income (expense):
Other income (expense), net	272.2	(82.9)	246.8	(9.1)
Interest expense	(9.7)	(8.0)	(15.8)	(15.7)
Total other income (expense)	262.5	(90.9)	231.0	(24.8)
Income before income taxes	918.9	224.7	1,587.5	770.8
Income tax expense	21.6	31.6	65.6	116.6
Net income	$ 897.3	$ 193.1	$ 1,521.9	$ 654.2
Net income per share - basic (in dollars per share)	$ 8.19	$ 1.77	$ 13.87	$ 6.00
Net income per share - diluted (in dollars per share)	$ 7.61	$ 1.68	$ 13.03	$ 5.69
Weighted average shares outstanding - basic (in shares)	109.6	109.2	109.7	109.1
Weighted average shares outstanding - diluted (in shares)	117.9	114.6	116.8	115.0
Statements of Comprehensive Income
Net income	$ 897.3	$ 193.1	$ 1,521.9	$ 654.2
Other comprehensive income (loss), net of tax:
Unrealized gain on debt securities	44.6	14.4	15.8	30.5
Unrealized loss on cash flow hedges	0.0	(1.4)	(1.4)	(2.4)
Comprehensive income	941.9	206.1	1,536.3	682.3
Product
Revenues:
Revenues	1,226.9	1,205.3	2,463.6	2,309.7
Expenses:
Cost of goods sold	102.5	67.0	181.3	137.9
Collaboration and contract manufacturing
Expenses:
Cost of goods sold	173.0	78.8	311.5	180.0
Sanofi \| Product and service, other
Revenues:
Revenues	269.1	75.8	516.0	57.8
Bayer \| Product and service, other
Revenues:
Revenues	244.2	277.2	525.6	541.2
Other \| Product and service, other
Revenues:
Revenues	$ 211.8	$ 19.5	$ 275.0	$ 41.7

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Class A Stock	Common Stock
Beginning Balance (in shares) at Dec. 31, 2018							(4.0)	1.9	111.1
Beginning Balance at Dec. 31, 2018	$ 8,757.3	$ 9.7	$ 3,911.6	$ 5,254.3	$ 9.7	$ (12.3)	$ (396.4)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)									0.6
Issuance of Common Stock for equity awards granted under long-term incentive plans	140.9		140.9
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(10.7)		(10.7)
Issuance/distribution of Common Stock for 401(k) Savings Plan	10.5		4.3				$ 6.2
Issuance/distribution of Common Stock in connection with 401(k) Savings Plan (in shares)							0.1
Repurchases of Common Stock (in shares)							(0.1)
Repurchases of Common Stock	(54.0)						$ (54.0)
Stock-based compensation charges	114.8		114.8
Net income	461.1			461.1
Other comprehensive income (loss), net of tax	15.1					15.1
Ending Balance (in shares) at Mar. 31, 2019							(4.0)	1.9	111.7
Ending Balance at Mar. 31, 2019	9,444.7		4,160.9	5,725.1		2.8	$ (444.2)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Dec. 31, 2018							(4.0)	1.9	111.1
Beginning Balance at Dec. 31, 2018	8,757.3	$ 9.7	3,911.6	5,254.3	$ 9.7	(12.3)	$ (396.4)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	654.2
Ending Balance (in shares) at Jun. 30, 2019							(4.0)	1.9	111.9
Ending Balance at Jun. 30, 2019	9,755.9		4,263.6	5,918.2		15.8	$ (441.8)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Mar. 31, 2019							(4.0)	1.9	111.7
Beginning Balance at Mar. 31, 2019	9,444.7		4,160.9	5,725.1		2.8	$ (444.2)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)									0.3
Issuance of Common Stock for equity awards granted under long-term incentive plans	13.9		13.9
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)									(0.1)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(29.7)		(29.7)
Issuance/distribution of Common Stock for 401(k) Savings Plan	11.7		9.3				$ 2.4
Stock-based compensation charges	109.2		109.2
Net income	193.1			193.1
Other comprehensive income (loss), net of tax	13.0					13.0
Ending Balance (in shares) at Jun. 30, 2019							(4.0)	1.9	111.9
Ending Balance at Jun. 30, 2019	9,755.9		4,263.6	5,918.2		15.8	$ (441.8)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Dec. 31, 2019							(4.9)	1.8	113.3
Beginning Balance at Dec. 31, 2019	11,089.7		4,428.6	7,379.8		21.1	$ (739.9)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)									3.1
Issuance of Common Stock for equity awards granted under long-term incentive plans	817.4		817.4
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)									(0.4)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(155.1)		(155.1)
Issuance/distribution of Common Stock for 401(k) Savings Plan	14.6		12.5				$ 2.1
Issuance/distribution of Common Stock in connection with 401(k) Savings Plan (in shares)							0.0
Repurchases of Common Stock (in shares)							(0.8)
Repurchases of Common Stock	(336.0)						$ (336.0)
Stock-based compensation charges	108.0		108.0
Net income	624.6			624.6
Other comprehensive income (loss), net of tax	(30.2)					(30.2)
Ending Balance (in shares) at Mar. 31, 2020							(5.7)	1.8	116.0
Ending Balance at Mar. 31, 2020	12,133.0		5,211.4	8,004.4		(9.1)	$ (1,073.8)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Dec. 31, 2019							(4.9)	1.8	113.3
Beginning Balance at Dec. 31, 2019	11,089.7		4,428.6	7,379.8		21.1	$ (739.9)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,521.9
Ending Balance (in shares) at Jun. 30, 2020							(15.6)	1.8	119.8
Ending Balance at Jun. 30, 2020	9,057.4		6,263.0	8,901.7		35.5	$ (6,142.9)	$ 0.0	$ 0.1
Beginning Balance (in shares) at Mar. 31, 2020							(5.7)	1.8	116.0
Beginning Balance at Mar. 31, 2020	12,133.0		5,211.4	8,004.4		(9.1)	$ (1,073.8)	$ 0.0	$ 0.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Common Stock for equity awards granted under long-term incentive plans (in shares)									4.4
Issuance of Common Stock for equity awards granted under long-term incentive plans	1,355.5		1,355.5
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations (in shares)									(0.6)
Common Stock tendered upon exercise of stock options and vesting of restricted stock for employee tax obligations	(416.5)		(416.5)
Issuance/distribution of Common Stock for 401(k) Savings Plan	10.1		7.4				$ 2.7
Issuance/distribution of Common Stock in connection with 401(k) Savings Plan (in shares)							0.0
Repurchases of Common Stock (in shares)							(9.9)
Repurchases of Common Stock	(5,071.8)						$ (5,071.8)
Stock-based compensation charges	105.2		105.2
Net income	897.3			897.3
Other comprehensive income (loss), net of tax	44.6					44.6
Ending Balance (in shares) at Jun. 30, 2020							(15.6)	1.8	119.8
Ending Balance at Jun. 30, 2020	$ 9,057.4		$ 6,263.0	$ 8,901.7		$ 35.5	$ (6,142.9)	$ 0.0	$ 0.1

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 1,521.9	$ 654.2
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	114.9	103.1
Non-cash compensation expense	209.3	213.7
Other non-cash items, net	(175.8)	110.7
Deferred taxes	118.0	(125.3)
Changes in assets and liabilities:
Increase in Sanofi, trade, and other accounts receivable	(47.1)	(247.5)
Increase in inventories	(233.4)	(168.2)
Decrease in prepaid expenses and other assets	33.8	33.2
Increase in deferred revenue	78.9	129.8
Increase in accounts payable, accrued expenses, and other liabilities	20.9	381.6
Total adjustments	119.5	431.1
Net cash provided by operating activities	1,641.4	1,085.3
Cash flows from investing activities:
Purchases of marketable and other securities	(1,533.5)	(2,189.1)
Sales or maturities of marketable securities	2,843.7	745.9
Capital expenditures	(300.0)	(168.9)
Net cash provided by (used in) investing activities	1,010.2	(1,612.1)
Cash flows from financing activities:
Proceeds from bridge loan facility	1,500.0	0.0
Proceeds from issuance of Common Stock	2,168.0	155.1
Payments in connection with Common Stock tendered for employee tax obligations	(571.6)	(40.5)
Repurchases of Common Stock	(5,373.6)	(10.0)
Net cash (used in) provided by financing activities	(2,277.2)	104.6
Net increase (decrease) in cash, cash equivalents, and restricted cash	374.4	(422.2)
Cash, cash equivalents, and restricted cash at beginning of period	1,630.3	1,480.2
Cash, cash equivalents, and restricted cash at end of period	$ 2,004.7	$ 1,058.0

Interim Financial Statements

6 Months Ended

Jun. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Interim Financial Statements

Basis of Presentation

The interim Condensed Consolidated Financial Statements of Regeneron Pharmaceuticals, Inc. and its subsidiaries ("Regeneron," "Company," "we," "us," and "our") 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 condensed consolidated financial statements for such periods. The results of operations for any interim period are not necessarily indicative of the results for the full year. The December 31, 2019 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, 2019.

Certain reclassifications have been made to prior period amounts to conform with the current period's presentation.

Effective January 1, 2020, we changed the presentation of cost reimbursements from collaborators who are not deemed to be our customers from collaboration revenue to a reduction of the corresponding operating expense (i.e., either Research and development or Selling, general, and administrative) incurred by us. We also changed the presentation of amounts recognized in connection with up-front and development milestone payments received from collaboration revenue to Other operating income. We made these changes in presentation because we believe the new presentation is preferable, as it better reflects the nature of the Company’s costs incurred and revenues earned pursuant to arrangements with collaborators and enhances the comparability of our financial statements with industry peers.

The change in presentation has been applied retrospectively. The tables below present the impact of the change on the Company’s previously-filed Consolidated Balance Sheet as of December 31, 2019, the Condensed Consolidated Statement of Operations for the three and six months ended June 30, 2019, and the Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2019. The Company’s previously-filed balance sheet has been updated to reflect the addition of the caption Other liabilities for the presentation of up-front and development milestones paid by collaborators that are deferred. There was no impact on the Company’s previously-filed Consolidated Statements of Stockholders’ Equity.


	December 31, 2019
Balance Sheet Data:	As Previously Reported		Adjustments		As Revised
Accrued expenses and other current liabilities	$	1,086.8	$	124.6	$	1,211.4
Deferred revenue - Sanofi (current)	$	395.5	$	(85.0)	$	310.5
Deferred revenue - other (current)	$	196.2	$	(124.6)	$	71.6
Other liabilities - Sanofi (current)	—		$	85.0	$	85.0
Deferred revenue - Sanofi (noncurrent)	$	509.7	$	(482.0)	$	27.7
Deferred revenue - other (noncurrent)	$	109.3	$	(31.7)	$	77.6
Other liabilities - Sanofi (noncurrent)	—		$	482.0	$	482.0
Other noncurrent liabilities	$	286.0	$	31.7	$	317.7


	Three Months Ended June 30, 2019										Six Months Ended June 30, 2019
Statement of Operations Data:	As Previously Reported		Adjustments		As Revised		As Previously Reported		Adjustments		As Revised
Sanofi collaboration revenue	$	349.1	$	(273.3)	$	75.8	$	595.5	$	(537.7)	$	57.8
Bayer collaboration revenue	$	289.0	$	(11.8)	$	277.2	$	565.2	$	(24.0)	$	541.2
Other revenue	$	90.3	$	(70.8)	$	19.5	$	175.1	$	(133.4)	$	41.7
Total revenues	$	1,933.7	$	(355.9)	$	1,577.8	$	3,645.5	$	(695.1)	$	2,950.4

Research and development	$	1,048.3	$	(162.8)	$	885.5	$	1,690.1	$	(318.5)	$	1,371.6
Selling, general, and administrative	$	417.3	$	(122.7)	$	294.6	$	828.1	$	(242.4)	$	585.7
Cost of collaboration and contract manufacturing⁽¹⁾	$	85.5	$	(6.7)	$	78.8	$	193.8	$	(13.8)	$	180.0
Other operating (income) expense, net	—		$	(63.7)	$	(63.7)	—		$	(120.4)	$	(120.4)
Total operating expenses	$	1,618.1	$	(355.9)	$	1,262.2	$	2,849.9	$	(695.1)	$	2,154.8

⁽¹⁾ In addition to the reclassification of certain amounts in connection with the change in accounting presentation described above, the Company also reclassified certain immaterial reimbursements that were previously classified as collaboration revenue to Cost of collaboration and contract manufacturing.


	Six Months Ended June 30, 2019
Cash Flows Data:	As Previously Reported		Adjustments		As Revised
Cash flows from operating activities:
Increase in deferred revenue	$	401.1	$	(271.3)	$	129.8
Increase in accounts payable, accrued expenses, and other liabilities	$	110.3	$	271.3	$	381.6

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The extent to which the COVID-19 pandemic may directly or indirectly impact our business, financial condition, and results of operations is highly uncertain and subject to change. We considered the potential impact of the COVID-19 pandemic on our estimates and assumptions and there was not a material impact to our condensed consolidated financial statements as of and for the three and six months ended June 30, 2020; however, actual results could differ from those estimates and there may be changes to our estimates in future periods.

Recently Adopted Accounting Standards

We adopted Accounting Standards Update 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments ("ASU 2016-13"), as of January 1, 2020. ASU 2016-13 requires an entity to measure and recognize expected credit losses for certain financial instruments, including trade receivables, as an allowance that reflects the entity's current estimate of credit losses expected to be incurred. For available-for-sale debt securities with unrealized credit losses, the standard requires allowances to be recorded through net income instead of directly reducing the amortized cost of the investment under the previous other-than-temporary impairment model. The adoption of this standard did not have a material impact on our financial statements or a significant impact on our internal controls.

Product Sales

6 Months Ended

Jun. 30, 2020

Revenues [Abstract]

Product Sales

Net product sales consist of the following:


	Three Months Ended June 30,							Six Months Ended June 30,
Net Product Sales in the United States	2020		2019		2020			2019
EYLEA^®	$	1,113.7	$	1,160.3	$	2,285.7		$	2,234.4
Libtayo^®	63.3		40.8		125.0			67.6
Praluent^®	47.2		*		47.2		*	*
ARCALYST^®	2.7		4.2		5.7			7.7
	$	1,226.9	$	1,205.3	$	2,463.6		$	2,309.7

^* Effective April 1, 2020, the Company is solely responsible for the development and commercialization of Praluent in the United States and records net product sales of Praluent in the United States. See Note 3 for further details.

The Company had product sales to certain customers that accounted for more than 10% of total gross product revenue for the three and six months ended June 30, 2020 and 2019. Sales to each of these customers as a percentage of the Company's total gross product revenue are as follows:


	Three Months Ended June 30,						Six Months Ended June 30,
	2020		2019		2020		2019
Besse Medical, a subsidiary of AmerisourceBergen Corporation	53	%	56	%	53	%	57	%
McKesson Corporation	32	%	34	%	34	%	32	%

Collaboration, License, and Other Agreements

6 Months Ended

Jun. 30, 2020

Revenue from Contract with Customer [Abstract]

Collaboration, License, and Other Agreements

We have entered into various collaborative arrangements to research, develop, manufacture, and commercialize product candidates and utilize our technology platforms. Although each of these arrangements is unique in nature, such arrangements involve a joint operating activity where both parties are active participants in the activities of the collaboration and exposed to significant risks and rewards dependent on the commercial success of the activities.

In arrangements where we do not deem our collaborator to be our customer, payments to and from our collaborator are presented in our statement of operations based on the nature of our business operations, the nature of the arrangement, including the contractual terms, and the nature of the payments, as summarized in the table and further described below.


Nature/Type of Payment						Statement of Operations Presentation
Regeneron's share of profits or losses in connection with commercialization of products						Collaboration revenue
Reimbursement for manufacturing of commercial supplies						Collaboration revenue
Royalties and/or sales-based milestones earned						Collaboration revenue
Reimbursement of Regeneron's research and development expenses						Reduction to Research and development expenses
Regeneron's obligation for its share of collaborator's research and development expenses						Research and development expense
Up-front and development milestone payments to collaborator						Research and development expense
Reimbursement of Regeneron's commercialization-related expenses						Reduction to Selling, general, and administrative expense
Regeneron's obligation for its share of collaborator's commercialization-related expenses						Selling, general, and administrative expense
Regeneron's obligation to pay collaborator for its share of gross profits when Regeneron is deemed to be the principal						Cost of goods sold
Up-front and development milestones earned (when we have a combined unit of account which includes a license and providing research and development services)						Other operating income

In agreements involving multiple goods or services promised to be transferred to our collaborator, we must assess, at the inception of the contract, whether each promise represents a separate obligation (i.e., is "distinct"), or whether such promises should be combined as a single unit of account. When we have a combined unit of account which includes a license and providing research and development services to our collaborator, recognition of up-front payments and development milestones earned from our collaborator is deferred (as a liability) and recognized over the development period (i.e., over time). In arrangements where we satisfy our obligation(s) during the development phase over time, we recognize amounts initially deferred over time typically using an input method on the basis of our research and development costs incurred relative to the total expected cost which determines the extent of our progress toward completion. We review our estimates each period and make revisions to such estimates as necessary.

When we are entitled to reimbursement of all or a portion of the research and development expenses that we incur under a collaboration, we record those reimbursable amounts in the period in which such costs are incurred. In connection with the commercialization phase of our collaborative arrangements, we may be obligated to perform commercialization-related activities on behalf of the collaboration. If we are reimbursed for all or a portion of costs incurred for the commercialization-related activities, we record those reimbursable amounts in the period in which such costs are incurred.

Under certain of the Company's collaboration agreements, product sales and cost of sales may be recorded by the Company's collaborators as they are deemed to be the principal in the transaction. In arrangements where we:

•are obligated to use commercially reasonable efforts to supply commercial product to our collaborator, we may be reimbursed for our manufacturing costs as commercial product is shipped to the collaborator; however, recognition of such cost reimbursements is deferred until the product is sold by our collaborator to third-party customers;

•share in any profits or losses arising from the commercialization of such products, we record our share of the variable consideration, representing net product sales less cost of goods sold and shared commercialization and other expenses, in the period in which such underlying sales occur and costs are incurred by the collaborator; and

•receive royalties and/or sales-based milestone payments from our collaborator, we recognize such amounts in the period earned.

Our collaborators provide us with estimates of product sales and our share of profits or losses, as applicable, for such quarter. These estimates are reconciled to actual results in the subsequent fiscal quarter, and collaboration revenue is adjusted accordingly, as necessary.

a. Sanofi

Amounts recognized in our Statements of Operations in connection with our collaborations with Sanofi are detailed below:


	Statement of Operations Classification	Three Months Ended June 30,									Six Months Ended June 30,
				2020			2019			2020			2019
Antibody:
Regeneron's share of profits in connection with commercialization of antibodies	Sanofi collaboration revenue	$	171.9		$	38.8		$	342.8		$	11.0
Reimbursement for manufacturing of commercial supplies	Sanofi collaboration revenue	$	100.6		$	43.9		$	180.7		$	58.4
Reimbursement of research and development expenses	Reduction of Research and development expense	$	51.3		$	81.8		$	128.9		$	156.3
Regeneron's obligation for its share of Sanofi research and development expenses	Research and development expense	$	(24.9)		$	(12.2)		$	(41.6)		$	(19.6)
Reimbursement of commercialization-related expenses	Reduction of Selling, general, and administrative expense	$	86.0		$	121.1		$	177.2		$	237.7

Immuno-oncology:
Regeneron's share of losses in connection with commercialization of Libtayo outside the United States	Sanofi collaboration revenue	$	(6.4)		$	(6.9)		$	(12.6)		$	(11.6)
Reimbursement for manufacturing of commercial supplies	Sanofi collaboration revenue	$	3.0		—			$	5.1		—
Reimbursement of research and development expenses	Reduction of Research and development expense	$	47.0		$	36.5		$	86.9		$	82.9
Reimbursement of commercialization-related expenses	Reduction of Selling, general, and administrative expense	$	14.3		$	1.8		$	24.7		$	4.0
Regeneron's obligation for Sanofi's share of Libtayo U.S. gross profits	Cost of goods sold	$	(28.2)		$	(19.0)		$	(55.0)		$	(31.4)
Amounts recognized in connection with up-front payments received	Other operating income	$	20.5		$	29.0		$	37.0		$	55.3

See Note 8 and Note 10 for information regarding Sanofi's sale of our Common Stock during the second quarter of 2020.

Antibody

The Company is party to a global, strategic collaboration with Sanofi to discover, develop, and commercialize fully human monoclonal antibodies (the "Antibody Collaboration"). Under the companies' Antibody License and Collaboration Agreement (the "LCA"), 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 generally shared 80% by Sanofi and 20% by Regeneron. All other agreed-upon worldwide development expenses incurred by both companies are funded by Sanofi.

Effective January 2018, the Company and Sanofi entered into a letter agreement (the "Letter Agreement") in connection with, among other matters, the allocation of additional funds to certain activities relating to dupilumab and REGN3500 (collectively, the "Dupilumab/REGN3500 Eligible Investments"). Refer to the "Immuno-Oncology" section below for further details regarding the Letter Agreement and Note 10 for additional information regarding shares purchased by us from Sanofi during the three and six months ended June 30, 2020 and 2019.

Sanofi leads commercialization activities for products developed under the Antibody Collaboration, subject to the Company's right to co-commercialize such products. See discussion below related to the development and commercialization of Praluent effective April 1, 2020. In addition to profit and loss sharing, the Company is entitled to receive up to $250.0 million in sales

milestone payments, with milestone payments commencing after aggregate annual sales of antibodies outside the United States (including Praluent) exceed $1.0 billion on a rolling twelve-month basis.

The following table summarizes contract balances in connection with the Company's Antibody Collaboration with Sanofi:


	June 30,		December 31,
	2020		2019
Accounts receivable	$	383.1	$	272.7
Deferred revenue	$	405.5	$	328.8

In April 2020, the Company and Sanofi entered into an amendment to the LCA in connection with, among other things, the removal of Praluent from the LCA such that (i) effective April 1, 2020, the LCA no longer governs the development, manufacture, or commercialization of Praluent and (ii) the quarterly period ended March 31, 2020 is the last quarter for which Sanofi and the Company will share profits and losses for Praluent under the LCA. The parties also entered into a Praluent Cross License & Commercialization Agreement (the "Praluent Agreement") pursuant to which, effective April 1, 2020, the Company, at its sole cost, is solely responsible for the development and commercialization of Praluent in the United States, and Sanofi, at its sole cost, is solely responsible for the development and commercialization of Praluent outside of the United States. Under the Praluent Agreement, Sanofi will pay the Company a 5% royalty on Sanofi’s net product sales of Praluent outside the United States until March 31, 2032. The Company will not owe Sanofi royalties on the Company’s net product sales of Praluent in the United States. Although each party will be responsible for manufacturing Praluent for its respective territory, the parties have entered into definitive supply agreements under which, for a certain transitional period, the Company will continue to supply drug substance to Sanofi and Sanofi will continue to supply finished product to Regeneron.

With respect to any intellectual property or product liability litigation relating to Praluent, the parties have agreed that, effective April 1, 2020, Regeneron and Sanofi each will be solely responsible for any such litigation (including damages and other costs and expenses thereof) in the United States and outside the United States, respectively, arising out of Praluent sales or other activities on or after April 1, 2020 (subject to Sanofi's right to set off a portion of any third-party royalty payments resulting from certain patent litigation proceedings against up to 50% of any Praluent royalty payment owed to Regeneron). The parties will each bear 50% of any damages arising out of Praluent sales or other activities prior to April 1, 2020. See Note 12 for discussion of legal proceedings related to Praluent.

Immuno-Oncology

In 2015, the Company and Sanofi entered into a collaboration to discover, develop, and commercialize antibody-based cancer treatments in the field of immuno-oncology (the "IO Collaboration"). The IO Collaboration is governed by an Amended and Restated Immuno-oncology Discovery and Development Agreement ("Amended IO Discovery Agreement"), and an Immuno-oncology License and Collaboration Agreement ("IO License and Collaboration Agreement").

Effective December 31, 2018, the Company and Sanofi entered into the Amended IO Discovery Agreement, which narrowed the scope of the existing discovery and development activities conducted by the Company ("IO Development Activities") under the 2015 IO Discovery Agreement to developing therapeutic bispecific antibodies targeting (i) BCMA and CD3 (the "BCMAxCD3 Program") and (ii) MUC16 and CD3 (the "MUC16xCD3 Program") through clinical proof-of-concept. If Sanofi exercises its option to license rights to a BCMAxCD3 Program antibody or MUC16xCD3 Program antibody thereunder, it will co-develop these drug candidates with the Company through product approval. Sanofi will fund development costs up front for a BCMAxCD3 Program antibody and we will reimburse half of the total development costs for such antibody from our share of future IO Collaboration profits to the extent they are sufficient for this purpose. In addition, we and Sanofi will share equally, on an ongoing basis, the development costs for a MUC16xCD3 Program antibody.

Under the terms of the IO License and Collaboration Agreement, the parties are co-developing and co-commercializing Libtayo (cemiplimab), an antibody targeting the receptor known as programmed cell death protein 1 (PD-1). The parties share equally, on an ongoing basis, agreed-upon development and commercialization expenses for Libtayo. Pursuant to the Letter Agreement, the Libtayo development budget was increased and the Company has agreed to allow Sanofi to satisfy in whole or in part its funding obligations with respect to the Libtayo development and Dupilumab/REGN3500 Eligible Investments by selling certain shares of our Common Stock directly or indirectly owned by Sanofi through September 30, 2020. If Sanofi desires to sell shares of our Common Stock during the term of the Letter Agreement to satisfy a portion or all of its funding obligations for the Libtayo development and/or Dupilumab/REGN3500 Eligible Investments, we may elect to purchase, in whole or in part, such

shares from Sanofi. See Note 10 for additional information regarding shares purchased by us from Sanofi during the three and six months ended June 30, 2020 and 2019.

The Company has principal control over the development of Libtayo and leads commercialization activities in the United States (see Note 2 for related product sales information), while Sanofi leads commercialization activities outside of the United States and the parties equally share profits and losses from worldwide sales.

The following table summarizes contract balances in connection with the Company's IO Collaboration with Sanofi:


	June 30,		December 31,
	2020		2019
Accounts receivable, net	$	(2.2)	$	(16.7)
Deferred revenue	$	12.5	$	9.4
Other liabilities	$	486.7	$	558.6

Other liabilities include up-front payments received from Sanofi for which recognition has been deferred.

The aggregate amount of the estimated consideration under the IO Collaboration related to the Company's obligation that was unsatisfied (or partially unsatisfied) as of June 30, 2020 was $1.020 billion. This amount is expected to be recognized over the remaining period in which the Company is obligated to satisfy its obligation in connection with performing development activities.

b. Bayer

Amounts recognized in our Statements of Operations in connection with our Bayer EYLEA collaboration are as follows:


	Statement of Operations Classification	Three Months Ended June 30,									Six Months Ended June 30,
				2020			2019			2020			2019
Regeneron's net profit in connection with commercialization of EYLEA outside the United States	Bayer collaboration revenue	$	230.9		$	269.0		$	484.7		$	518.3
Reimbursement for manufacturing of commercial supplies	Bayer collaboration revenue	$	13.3		$	8.2		$	40.9		$	22.9
Reimbursement of development expenses	Reduction of Research and development expense	$	10.8		$	8.0		$	22.8		$	10.6
Regeneron's obligation for its share of Bayer research and development expenses	Research and development expense	$	(5.3)		$	(2.0)		$	(13.4)		$	(6.6)
Reimbursement of other expenses	Cost of collaboration and contract manufacturing	$	1.6		$	4.1		$	3.3		$	12.9

The Company is party to a license and collaboration agreement with Bayer for the global development and commercialization of EYLEA outside the United States. Bayer markets EYLEA outside the United States, where, for countries other than Japan, the companies share equally in profits and losses from sales of EYLEA. In Japan, the Company is currently entitled to receive a tiered percentage of between 33.5% and 40.0% of EYLEA net product sales through 2021, and thereafter, the companies will share equally in profits and losses from sales of EYLEA. In addition, the Company and Bayer share the funding of agreed-upon EYLEA development costs.

The following table summarizes contract balances in connection with our Bayer EYLEA collaboration:


	June 30,		December 31,
	2020		2019
Accounts receivable - other	$	245.8	$	311.6
Deferred revenue	$	125.3	$	123.0

c. Teva

In 2016, the Company and Teva entered into a collaboration agreement (the "Teva Collaboration Agreement") to develop and commercialize fasinumab globally, excluding certain Asian countries that are subject to our collaboration agreement with Mitsubishi Tanabe Pharma Corporation. The Company leads global development activities, and the parties share development costs equally, on an ongoing basis, under a global development plan. The Company is also responsible for the manufacture and supply of fasinumab globally.

Amounts recognized in our Statements of Operations in connection with the Teva Collaboration Agreement are as follows:


	Statement of Operations Classification	Three Months Ended June 30,									Six Months Ended June 30,
				2020			2019			2020			2019
Reimbursement of research and development expenses	Reduction of Research and development expense	$	31.0		$	36.5		$	56.2		$	68.7
Amounts recognized in connection with up-front and development milestone payments received	Other operating income	$	20.7		$	24.5		$	37.3		$	46.0

The following table summarizes contract balances in connection with the Teva Collaboration Agreement:


	June 30,		December 31,
	2020		2019
Accounts receivable - other	$	28.5	$	21.2
Other liabilities	$	77.9	$	114.4

Other liabilities include up-front and development milestone payments received from Teva for which recognition has been deferred.

The aggregate amount of estimated consideration under the Teva Collaboration Agreement related to the Company's obligation that was unsatisfied (or partially unsatisfied) as of June 30, 2020 was $173.3 million. This amount is expected to be recognized over the remaining period in which the Company is obligated to satisfy its obligation in connection with performing development activities.

d. Intellia

In 2016, we entered into a license and collaboration agreement with Intellia Therapeutics, Inc. to advance CRISPR/Cas9 gene-editing technology for in vivo therapeutic development. The parties collaborate to conduct research for the discovery, development, and commercialization of new therapies, in addition to the research and technology development of the CRISPR/Cas9 platform.

Under the terms of the 2016 agreement, the parties agreed to a target selection process, whereby the Company may obtain exclusive rights in up to 10 targets to be chosen by the Company during the collaboration term, subject to various adjustments and limitations set forth in the agreement. Certain targets that either we or Intellia select pursuant to the target selection process may be subject to a co-development and co-commercialization arrangement at our option or Intellia’s option, as applicable.

In May 2020, we expanded our existing collaboration with Intellia to provide us with rights to develop products for additional in vivo CRISPR/Cas9-based therapeutic targets and for the parties to jointly develop potential products for the treatment of hemophilia A and B. In addition, we also received non-exclusive rights to independently develop and commercialize ex vivo gene edited products. In connection with the agreement, we made a $70.0 million up-front payment, which was recorded to Research and development expense in the second quarter of 2020, and purchased 925,218 shares of Intellia common stock for an aggregate purchase price of $30.0 million. The amount paid in excess of the fair market value of the shares purchased, or $15.0 million, was also recorded to Research and development expense in the second quarter of 2020.

e. Biomedical Advanced Research Development Authority ("BARDA")

In the first quarter of 2020, we announced an expansion of our Other Transaction Agreement ("OTA") with BARDA, pursuant to which U.S. Department of Health and Human Services ("HHS") is obligated to fund 80% of our costs incurred for certain research and development activities related to COVID-19 treatments. In July 2020, we entered into an agreement with entities acting at the direction of BARDA and the U.S. Department of Defense to manufacture and deliver filled and finished REGN-COV2 to the U.S. Government. The agreement could result in payments to the Company of up to $450.2 million in the aggregate for bulk manufacturing of the drug substance, as well as fill/finish and storage activities.

Net Income Per Share

6 Months Ended

Jun. 30, 2020

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,						Six Months Ended June 30,
	2020		2019		2020		2019
Net income - basic and diluted	$	897.3	$	193.1	$	1,521.9	$	654.2

(Shares in millions)
Weighted average shares - basic	109.6		109.2		109.7		109.1
Effect of dilutive securities:
Stock options	7.8		5.4		6.7		5.9
Restricted stock	0.5		—		0.4		—
Weighted average shares - diluted	117.9		114.6		116.8		115.0

Net income per share - basic	$	8.19	$	1.77	$	13.87	$	6.00
Net income per share - diluted	$	7.61	$	1.68	$	13.03	$	5.69

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


	Three Months Ended June 30,			Six Months Ended June 30,
(Shares in millions)	2020	2019	2020	2019
Stock options	0.1	18.3	3.5	18.1
Restricted stock	—	0.4	—	—

Marketable Securities

6 Months Ended

Jun. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable securities as of June 30, 2020 and December 31, 2019 consist of both available-for-sale debt securities of investment grade issuers (see below and Note 6) as well as equity securities of publicly traded companies (see Note 6).

The following tables summarize the Company's investments in available-for-sale debt securities:


	Amortized		Unrealized						Fair
As of June 30, 2020	Cost Basis		Gains		Losses		Value
Corporate bonds	$	2,393.2	$	41.9	$	(0.7)	$	2,434.4
U.S. government and government agency obligations	81.6		1.1		—		82.7
Sovereign bonds	27.0		1.2		—		28.2
Commercial paper	283.1		0.6		—		283.7
Certificates of deposit	105.4		0.1		—		105.5
	$	2,890.3	$	44.9	$	(0.7)	$	2,934.5

As of December 31, 2019
Corporate bonds	$	3,960.5	$	27.8	$	(0.2)	$	3,988.1
U.S. government and government agency obligations	54.3		0.2		(0.1)		54.4
Sovereign bonds	26.9		0.4		—		27.3
Commercial paper	92.3		—		—		92.3
Certificates of deposit	72.3		0.1		—		72.4
	$	4,206.3	$	28.5	$	(0.3)	$	4,234.5

The Company classifies its investments in available-for-sale debt securities based on their contractual maturity dates. The available-for-sale debt securities listed as of June 30, 2020 mature at various dates through July 2025. The fair values of available-for-sale debt security investments by contractual maturity consist of the following:


	June 30,		December 31,
	2020		2019
Maturities within one year	$	1,152.0	$	1,596.5
Maturities after one year through five years	1,779.6		2,638.0
Maturities after five years	2.9		—
	$	2,934.5	$	4,234.5

The following table shows the fair value of the Company's available-for-sale debt securities that have unrealized losses, aggregated by investment category and length of time that the individual securities have been in a continuous loss position.


	Less than 12 Months					12 Months or Greater					Total
As of June 30, 2020	Fair Value		Unrealized Loss		Fair Value	Unrealized Loss	Fair Value		Unrealized Loss
Corporate bonds	$	247.9	$	(0.7)	—	—	$	247.9	$	(0.7)

As of December 31, 2019
Corporate bonds	$	257.2	$	(0.2)	—	—	$	257.2	$	(0.2)
U.S. government and government agency obligations	17.3		(0.1)		—	—	17.3		(0.1)
	$	274.5	$	(0.3)	—	—	$	274.5	$	(0.3)

For the three and six months ended June 30, 2020, realized gains on sales of marketable securities were $28.0 million and $28.3 million, respectively, and realized losses were not material. There were no realized losses on sales of marketable securities, and realized gains were not material, for the three and six months ended June 30, 2019.

With respect to marketable securities, for the three and six months ended June 30, 2020 and 2019, amounts reclassified from Accumulated other comprehensive income into Other income (expense), net were related to realized gains on sales of available-for-sale debt securities (as described above).

Fair Value Measurements

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

The table below summarizes the Company's assets which are measured at fair value on a recurring basis. The following fair value hierarchy is used to classify assets, based on inputs to valuation techniques utilized to measure fair value:

•Level 1 - Quoted prices in active markets for identical assets

•Level 2 - Significant other observable inputs, such as 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

•Level 3 - Significant other unobservable inputs


			Fair Value Measurements at Reporting Date
As of June 30, 2020	Fair Value		Level 1		Level 2
Available-for-sale debt securities:
Corporate bonds	$	2,434.4	—		$	2,434.4
U.S. government and government agency obligations	82.7		—		82.7
Sovereign bonds	28.2		—		28.2
Commercial paper	283.7		—		283.7
Certificates of deposit	105.5		—		105.5
Equity securities (unrestricted)	37.8		$	37.8	—
Equity securities (restricted)	767.3		751.9		15.4
	$	3,739.6	$	789.7	$	2,949.9

As of December 31, 2019
Available-for-sale debt securities:
Corporate bonds	$	3,988.1	—		$	3,988.1
U.S. government and government agency obligations	54.4		—		54.4
Sovereign bonds	27.3		—		27.3
Commercial paper	92.3		—		92.3
Certificates of deposit	72.4		—		72.4
Equity securities (unrestricted)	61.6		$	61.6	—
Equity securities (restricted)	557.2		557.2		—
	$	4,853.3	$	618.8	$	4,234.5

The Company held certain restricted equity securities as of June 30, 2020 which are subject to transfer restrictions that expire at various dates through 2024.

During the three and six months ended June 30, 2020, we recorded $228.1 million and $171.3 million of net unrealized gains, respectively, on equity securities in Other income (expense), net. During the three and six months ended June 30, 2019, we recorded $116.9 million and $74.1 million, respectively, of net unrealized losses on equity securities in Other income (expense), net.

In addition to the investments summarized in the table above, as of June 30, 2020 and December 31, 2019, the Company had $70.6 million and $55.6 million, respectively, in equity investments that do not have a readily determinable fair value. These investments are recorded within Other noncurrent assets.

- 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

Inventories

6 Months Ended

Jun. 30, 2020

Inventory Disclosure [Abstract]

Inventories

Inventories consist of the following:


	June 30,		December 31,
	2020		2019
Raw materials	$	306.3	$	216.3
Work-in-process	696.9		727.7
Finished goods	132.0		70.6
Deferred costs	505.7		400.9
	$	1,640.9	$	1,415.5

Deferred costs represent the costs of product manufactured and shipped to the Company's collaborators for which recognition of revenue has been deferred (see Note 3).

Debt	6 Months Ended
Debt	Jun. 30, 2020
Debt Disclosure [Abstract]
Debt	Debt As described in Note 10, we purchased shares of our Common Stock from Sanofi, in connection with Sanofi's secondary offering of our Common Stock held by Sanofi, with a combination of cash on hand, proceeds from the sale of marketable securities, and proceeds from loans under a $1.5 billion senior unsecured 364-day bridge loan facility (the "Bridge Facility") which was entered into in May 2020. The loans under the Bridge Facility bear interest at a variable interest rate based on either the London Interbank Offered Rate or the alternate base rate, plus an applicable margin that varies with our debt rating and total leverage ratio. The interest rate on the loans under the Bridge Facility was 2.75% as of June 30, 2020. The Bridge Facility will mature, and all amounts outstanding thereunder will become due and payable, in May 2021. Amounts borrowed under the Bridge Facility may be prepaid at any time without premium or penalty. As of June 30, 2020, $1.5 billion remained outstanding under the Bridge Facility. The credit agreement governing the Bridge Facility (the "Bridge Credit Agreement") contains financial and operating covenants, which are substantially similar to the covenants set forth in our existing $750.0 million senior unsecured five-year revolving credit facility. Financial covenants include a maximum total leverage ratio and a minimum interest expense coverage ratio. We were in compliance with all covenants of the Bridge Credit Agreement as of June 30, 2020.

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company is subject to U.S. federal, state, and foreign income taxes. The Company's effective tax rate was 2.4% and 14.1% for the three months ended June 30, 2020 and 2019, respectively, and 4.1% and 15.1% for the six months ended June 30, 2020 and 2019, respectively. The Company's effective tax rate for the three and six months ended June 30, 2020 was positively impacted, compared to the U.S. federal statutory rate, primarily by stock-based compensation, and, to a lesser extent, income earned in foreign jurisdictions with tax rates lower than the U.S. federal statutory rate and federal tax credits for research activities. The Company's effective tax rate for the three and six months ended June 30, 2019 was positively impacted, compared to the U.S. federal statutory rate, primarily by income earned in foreign jurisdictions with tax rates lower than the U.S. federal statutory rate, stock-based compensation, federal tax credits for research activities, and, to a lesser extent, the foreign-derived intangible income deduction, partly offset by the taxation of certain global intangible low-taxed income and the non-deductible Branded Prescription Drug Fee.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Stockholders' Equity

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Stockholders' Equity

Share Repurchase Program

In November 2019, our board of directors authorized a share repurchase program to repurchase up to $1.0 billion of our Common Stock. The share repurchase program permits the Company to effect repurchases through a variety of methods,

including open-market transactions (including pursuant to a trading plan adopted in accordance with Rule 10b5-1 of the Exchange Act), privately negotiated transactions, accelerated share repurchases, block trades, and other transactions in compliance with Rule 10b-18 of the Exchange Act. Repurchases may be made from time to time at management’s discretion, and the timing and amount of any such repurchases will be determined based on share price, market conditions, legal requirements, and other relevant factors. The program has no time limit and can be discontinued at any time. There can be no assurance as to the timing or number of shares of any repurchases in the future.

The table below summarizes the shares of our Common Stock we repurchased during 2020 under the program and the cost of the shares received, which were recorded as Treasury Stock. There were no shares repurchased under the program during the three months ended June 30, 2020.


	Six Months Ended June 30, 2020
Number of shares repurchased	719,167
Total cost of shares received	$	272.8

As of June 30, 2020, the Company had $473.1 million which remained available for share repurchases under the program.

Sanofi Funding of Certain Development Costs

As described in Note 3, effective January 2018, we have agreed to allow Sanofi to satisfy in whole or in part its funding obligations with respect to Libtayo development costs and/or Dupilumab/REGN3500 Eligible Investments by selling our Common Stock directly or indirectly owned by Sanofi. The table below summarizes the shares of our Common Stock Sanofi elected to sell, and we elected to purchase, to satisfy Sanofi's funding obligations and the cost of the shares received, which were recorded as Treasury Stock:


	Three Months Ended June 30,					Six Months Ended June 30,
	2020		2019	2020		2019
Libtayo:
Number of shares purchased (by issuing a credit towards the amount owed by Sanofi)	34,050		—	77,677		106,972
Total cost of shares received	$	20.3	—	$	41.7	$	44.0

Dupilumab/REGN3500:
Number of shares purchased (in cash)	86,184		—	171,471		24,143
Total cost of shares received	$	51.5	—	$	93.3	$	10.0

As of June 30, 2020, 279,766 shares of our Common Stock remained available for sale by Sanofi to satisfy its funding obligations with respect to Libtayo development costs and/or Dupilumab/REGN3500 Eligible Investments through September 30, 2020.

Additional Stock Purchased from Sanofi

In May 2020, a secondary offering of 13,014,646 shares of our Common Stock (the "Secondary Offering") held by Sanofi was completed. In connection with the Secondary Offering, we also purchased 9,806,805 shares directly from Sanofi for an aggregate purchase amount of $5 billion (the "Stock Purchase"). As a result of the Secondary Offering and the Stock Purchase, Sanofi disposed of all of its shares of our Common Stock, other than 400,000 shares that it retained as of the closing of the Secondary Offering and the Stock Purchase (which Sanofi has used, and may continue to use, for the funding of certain development costs described above). See Note 8 for additional information.

Statement of Cash Flows

6 Months Ended

Jun. 30, 2020

Supplemental Cash Flow Information [Abstract]

Statement of Cash Flows

The following provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Condensed Consolidated Balance Sheet to the total of the same such amounts shown in the Condensed Consolidated Statement of Cash Flows:


	June 30,		June 30,
	2020		2019
Cash and cash equivalents	$	1,992.2	$	1,045.5
Restricted cash included in Other noncurrent assets	12.5		12.5
Total cash, cash equivalents, and restricted cash shown in the Condensed Consolidated Statement of Cash Flows	$	2,004.7	$	1,058.0

Restricted cash consists of amounts held by financial institutions pursuant to contractual arrangements.

Supplemental disclosure of non-cash investing and financing activities

Included in accounts payable, accrued expenses, and other liabilities as of June 30, 2020 and December 31, 2019 were $87.4 million and $133.7 million, respectively, of accrued capital expenditures. Included in accounts payable, accrued expenses, and other liabilities as of June 30, 2019 and December 31, 2018 were $74.7 million and $54.5 million, respectively, of accrued capital expenditures.

Legal Matters	6 Months Ended
Legal Matters	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Legal Matters	Legal Matters From time to time, the Company is a party to legal proceedings in the course of the Company's business. Costs associated with the Company's involvement in legal proceedings are expensed as incurred. The outcome of any such proceedings, regardless of the merits, is inherently uncertain. The Company recognizes accruals for loss contingencies associated with such proceedings when it is probable that a liability will be incurred and the amount of loss can be reasonably estimated. As of June 30, 2020 and December 31, 2019, the Company had accruals for loss contingencies of $132.2 million and $100.0 million, respectively. If the Company were unable to prevail in any such proceedings, its consolidated financial position, results of operations, and future cash flows may be materially impacted. Proceedings Relating to '287 Patent and '163 Patent The Company is a party to patent infringement litigation initiated by the Company involving its European Patent No. 1,360,287 (the "'287 Patent") and its European Patent No. 2,264,163 (the "'163 Patent"). Each of these patents concerns genetically engineered mice capable of producing chimeric antibodies that are part human and part mouse. Chimeric antibody sequences can be used to produce high-affinity fully human monoclonal antibodies. In these proceedings, the Company claims infringement of several claims of the '287 Patent and the '163 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 '163 Patent (as applicable). On September 25, 2013, the Company commenced patent infringement litigation against Kymab Ltd in the English High Court of Justice, Chancery Division, Patents Court, in London, asserting the '287 Patent and '163 Patent. Following a trial to adjudicate the claims of infringement and counterclaims of invalidity of the '287 Patent and the '163 Patent, the court issued a final judgment on February 1, 2016, finding that the asserted claims of the '287 and '163 Patents are novel, not obvious, and infringed by Kymab's genetically engineered mice. However, the court invalidated the '287 and '163 Patents on the ground of insufficiency. On appeal, the Court of Appeal (Civil Division of England and Wales) reversed the English High Court's decision and held that the '287 Patent and '163 Patent are both valid and infringed by Kymab and subsequently issued a final order, which enjoins Kymab from infringing the '287 Patent and '163 Patent (subject to certain exceptions) and requires Kymab to destroy or deliver to a third party all products and antibodies and cells engineered to produce antibodies which infringe the '287 Patent and '163 Patent (subject to certain exceptions). Thereafter, the Supreme Court of the United Kingdom granted Kymab's application for permission to appeal the order made by the Court of Appeal with respect to an issue of validity of the '287 Patent and the '163 Patent. An oral hearing was held on February 11–12, 2020. On June 24, 2020, the Supreme Court of the United Kingdom overturned the decision of the Court of Appeal on validity and held that the '287 and '163 Patents are each invalid on the ground of insufficiency. On July 8 and July 13, 2016, notices of opposition against the '163 Patent were filed in the European Patent Office (the "EPO") by Merus N.V. and Kymab and Novo Nordisk A/S, respectively. The notices assert, as applicable, lack of novelty, lack of inventive step, and insufficiency. Following an oral hearing before the Opposition Division of the EPO on February 5–7, 2018, the Opposition Division upheld the '163 Patent without amendments. Kymab, Merus, and Novo Nordisk each filed a notice of appeal of the Opposition Division's decision on February 9, 2018, May 25, 2018, and June 26, 2018, respectively. On January 7, 2019, Merus withdrew its appeal of the '163 Patent in the EPO in connection with the previously reported global settlement. Proceedings Relating to Praluent (alirocumab) Injection As described in greater detail below, the Company is currently a party to patent infringement actions initiated by Amgen Inc. (and/or its affiliated entities) against the Company and/or Sanofi (and/or the Company's and Sanofi's respective affiliated entities) in a number of jurisdictions relating to Praluent. See Note 3 for a description of the Company's and Sanofi's arrangement regarding the costs resulting from or associated with such actions. United States In the United States, Amgen has asserted claims of U.S. Patent Nos. 8,829,165 (the "'165 Patent") and 8,859,741 (the "'741 Patent"), and seeks a permanent injunction to prevent the Company and the Sanofi defendants from commercial manufacturing, using, offering to sell, or selling within the United States (as well as importing into the United States) (collectively, "Commercializing") Praluent. Amgen also seeks a judgment of patent infringement of the asserted patents, monetary damages (together with interest), costs and expenses of the lawsuits, and attorneys' fees. The first jury trial in this litigation (the "First Trial") was held in the United States District Court for the District of Delaware (the "District Court") from March 8 to March 16, 2016. During the course of the First Trial, the District Court ruled as a matter of law in favor of Amgen that the asserted patent claims were not obvious, and in favor of the Company and the Sanofi defendants that there was no willful infringement of the asserted patent claims by the Company or the Sanofi defendants. On March 16, 2016, the jury returned a verdict in favor of Amgen in the First Trial, finding that the asserted claims of the '165 and '741 Patents were not invalid based on either a lack of written description or a lack of enablement. On October 5, 2017, the United States Court of Appeals for the Federal Circuit (the "Federal Circuit") reversed in part the District Court's decision and remanded for a new trial on the issues of written description and enablement. In addition, it affirmed the District Court's ruling that Amgen's patents were not obvious. On January 3, 2019, the District Court held oral argument in the remanded proceedings on the Company and the Sanofi defendants' motion for judgment on the pleadings regarding Amgen's willful infringement claim. On January 18, 2019, the District Court entered an order (i) denying the Company and the Sanofi defendants' motion for summary judgment on validity, (ii) denying Amgen's motion for partial summary judgment on estoppel, and (iii) granting the Company and the Sanofi defendants' cross-motion for summary judgment on estoppel. On February 8, 2019, the District Court granted the Company and the Sanofi defendants' motion for judgment on the pleadings, thereby dismissing Amgen's claim of willful infringement. The second jury trial in this litigation (the "Second Trial") was held before the District Court in February 2019 to determine the validity of Amgen's asserted patent claims. On February 25, 2019, the jury returned a verdict in the Second Trial generally in favor of Amgen, finding that two claims of the '165 Patent and one claim of the '741 Patent were not invalid. The jury also found that two claims of the '165 Patent were invalid for lack of adequate written description while rejecting the lack of enablement challenges to those two claims. On August 28, 2019, the District Court ruled as a matter of law that Amgen's asserted patent claims are invalid based on lack of enablement. The District Court also conditionally denied the Company and the Sanofi defendants' motion for a new trial. On October 23, 2019, Amgen filed a notice of appeal of the District Court's decision with the Federal Circuit. On March 18, 2019, Amgen filed a renewed motion for a permanent injunction to prohibit the Company and the Sanofi defendants from Commercializing Praluent in the United States (a "Permanent Injunction"), and an oral hearing on this motion was held in June 2019. Previously, the Federal Circuit stayed and then vacated a Permanent Injunction granted by the District Court in connection with the First Trial. On August 28, 2019, the District Court dismissed as moot Amgen's renewed motion for a Permanent Injunction. Europe On July 25, 2016, Amgen filed a lawsuit against Regeneron, Sanofi-Aventis Groupe S.A., Sanofi-Synthelabo Limited, Aventis Pharma Limited, Sanofi Winthrop Industrie S.A., and Sanofi-Aventis Deutschland GmbH in the English High Court of Justice, Chancery Division, Patents Court, in London, seeking a declaration of infringement of Amgen's European Patent No. 2,215,124 (the "'124 Patent"), which pertains to PCSK9 monoclonal antibodies, by Praluent. The lawsuit also seeks a permanent injunction, damages, an accounting of profits, and costs and interest. On February 8, 2017, the court temporarily stayed this litigation on terms mutually agreed by the parties. Also on July 25, 2016, Amgen filed a lawsuit for infringement of the '124 Patent against Regeneron, Sanofi-Aventis Groupe S.A., Sanofi Winthrop Industrie S.A., and Sanofi-Aventis Deutschland GmbH in the Regional Court of Düsseldorf, Germany (the "Düsseldorf Regional Court"), seeking a permanent injunction, an accounting of marketing activities, a recall of Praluent and its removal from distribution channels, and damages. On November 14, 2017, the Düsseldorf Regional Court issued a decision staying the infringement proceedings until a decision of the Opposition Division of the EPO concerning the pending opposition filed by the Company, Sanofi, and several other opponents against the '124 Patent (as discussed below). Following Amgen's request to reopen the proceedings in light of the issuance of the Preliminary Opinion (as defined below), the Düsseldorf Regional Court held an oral hearing on September 11, 2018 and ruled on December 10, 2018 that the infringement proceedings would be reopened. On July 11, 2019, the Düsseldorf Regional Court found that Praluent infringes the '124 Patent and granted an injunction prohibiting the Company and Sanofi's manufacture, sale, and marketing of Praluent in Germany (the "July 11 Decision"). Amgen subsequently enforced the injunction and, as a result, commercialization of Praluent in Germany has been discontinued. On July 12, 2019, the Company and Sanofi appealed the July 11 Decision to the Higher Regional Court of Düsseldorf (the "Higher Regional Court"). An oral hearing on the merits of the appeal to the Higher Regional Court (originally scheduled for April 2, 2020) has been rescheduled for November 5, 2020. On August 5, 2019 and October 31, 2019, the Higher Regional Court denied the Company and Sanofi's requests for a stay of preliminary enforcement of the July 11 Decision pending the appeal on the merits. On September 26, 2016, Amgen filed a lawsuit for infringement of the '124 Patent in the Tribunal de grande instance in Paris, France against Regeneron, Sanofi-Aventis Groupe S.A., Sanofi Winthrop Industrie S.A., and Sanofi Chimie (subsequently added as a defendant). Amgen is seeking the prohibition of allegedly infringing activities with a €10,000 penalty per drug unit of Praluent produced in violation of the court order sought by Amgen; an appointment of an expert for the assessment of damages; disclosure of technical (including supply-chain) and accounting information to the expert and the court; provisional damages of €10.0 million (which would be awarded on an interim basis pending final determination); reimbursement of costs; publication of the ruling in three newspapers; and provisional enforcement of the decision to be issued, which would ensure enforcement of the decision (including any provisional damages) pending appeal. Amgen is not seeking a preliminary injunction in this proceeding at this time. On April 10, 2017, the Company and the Sanofi parties filed briefs seeking invalidation of certain of the claims of the '124 Patent, and Amgen filed a response on July 28, 2017. Oral hearing on this infringement lawsuit (originally scheduled for February 12, 2019) has yet to be rescheduled. On December 17, 2019, Amgen initiated a lawsuit alleging infringement of the Dutch designation of the '124 Patent in the District Court of The Hague in the Netherlands, against Sanofi-Aventis Netherlands B.V. and Sanofi-Aventis Groupe S.A. The Company has not been named as a defendant in this action. Amgen alleges, among other things, patent infringement based on the production, importation, and commercialization of Praluent (alirocumab) in the Netherlands. Amgen's requests are made on an accelerated basis and include, among other things, a request for a permanent injunction, damages, an order for customer information, a recall order, a destruction order, and an order for costs. A trial has been scheduled for October 30, 2020. On December 20, 2019, Amgen filed a lawsuit for infringement of the Italian designation of the '124 Patent in the Tribunale di Milano - Enterprise Chamber in Milan, Italy, against Sanofi-Aventis Groupe S.A., Sanofi Chimie, and Sanofi SpA. The Company has not been named as a defendant in this action. Amgen alleges that the production, importation, and commercialization of Praluent (alirocumab) in Italy infringes the '124 Patent. The writ of summons filed by Amgen seeks, among other things, a declaration of infringement, a permanent injunction, withdrawal of product from the market, and damages. On June 24, 2020, Amgen also filed a preliminary injunction motion against the Sanofi parties. On December 20, 2019, Amgen also filed a lawsuit alleging infringement of the Spanish designation of the '124 Patent in the Juzgado de lo Mercantil No. 5 (Commercial Court) in Barcelona, Spain, against Sanofi-Aventis, S.A. The Company has not been named as a defendant in this action. Amgen alleges, among other things, patent infringement based on the manufacture, offering for sale, introduction into the market, use, and importation or possession of Praluent (alirocumab) in Spain. Amgen seeks, among other things, a permanent injunction, withdrawal of Praluent from the market, seizure and destruction of Praluent from the market and in storage, and damages in the form of lost profits and costs and expenses. On May 12, 2020, the court stayed this lawsuit until October 30, 2020 on terms mutually agreed by the parties. The '124 Patent is also subject to opposition proceedings in the EPO seeking to invalidate certain of its claims, which were initiated by Sanofi on February 24, 2016 and, separately, by the Company, Sanofi, and several other opponents on November 24, 2016. On December 13, 2017, the Opposition Division of the EPO issued a preliminary, non-binding opinion (the "Preliminary Opinion") regarding the validity of the '124 Patent, indicating that it currently considers the claims of a new request filed by Amgen in response to the opposition to satisfy the requirements for patentability. An oral hearing on the oppositions against the '124 Patent was held on November 28–30, 2018, at which the Opposition Division upheld the validity of the '124 Patent's claims in amended form. The Company and Sanofi filed notices of appeal to the Technical Board of Appeal (the "TBA") of the EPO on November 30, 2018. An oral hearing before the TBA has been rescheduled for October 28–29, 2020. Other On May 19, 2017, Amgen filed a lawsuit for infringement of Amgen's Japanese Patent Nos. 5,906,333 (the "'333 Patent") and 5,705,288 (the "'288 Patent") in the Tokyo District Court Civil Division (the "Tokyo District Court") against Sanofi K.K. Amgen's complaint alleges that manufacturing, selling or otherwise transferring, and offering to sell or otherwise transfer Praluent (alirocumab) in Japan (as well as importing Praluent (alirocumab) into Japan) infringe the '333 and '288 Patents. The complaint further seeks a permanent injunction, disposal of product, and court costs. The Company has not been named as a defendant in this litigation. On January 17, 2019, the Tokyo District Court upheld the validity of the '333 Patent and '288 Patent and ordered a permanent injunction against Sanofi K.K. to stop manufacturing, selling or otherwise transferring, and offering to sell or otherwise transfer Praluent (alirocumab) in Japan (as well as importing Praluent (alirocumab) into Japan) and to dispose of all product. However, the Tokyo District Court stayed the enforcement of such injunction pending appeal to the Intellectual Property High Court of Japan (the "IPHC"). On January 30, 2019, Sanofi K.K. appealed the Tokyo District Court's decision in the infringement proceedings to the IPHC. Following an oral hearing on October 30, 2019, the IPHC affirmed the Tokyo District Court's decision in the infringement proceedings. Sanofi K.K. appealed the IPHC's decision in the infringement proceedings to the Supreme Court of Japan on November 12, 2019. On April 24, 2020, the Supreme Court of Japan declined to hear the appeal filed by Sanofi K.K. in the infringement proceedings and the injunction issued by the Tokyo District Court became effective. Sanofi K.K. subsequently complied with the injunction and, as a result, the commercialization of Praluent in Japan has been discontinued. On March 31, 2020, Amgen filed a related lawsuit in the Tokyo District Court against Sanofi K.K. seeking damages incurred by Amgen as a result of the finding of infringement of the '333 Patent and the '288 Patent. The Company has not been named as a defendant in this damages action. Proceedings Relating to Dupixent (dupilumab) Injection United States On March 20, 2017, the Company, Sanofi-Aventis U.S. LLC, and Genzyme Corporation filed a lawsuit against Amgen and Immunex Corporation, a wholly owned subsidiary of Amgen, in the United States District Court for the District of Massachusetts seeking a declaratory judgment that the Company's and the other plaintiffs' Commercializing of Dupixent does not directly or indirectly infringe U.S. Patent No. 8,679,487 (the "'487 Patent") owned by Immunex Corporation relating to antibodies that bind the human interleukin-4 receptor. On May 1, 2017, the Company and the other plaintiffs filed a notice of voluntary dismissal of this action without prejudice. On March 23, 2017, the Company, Sanofi-Aventis U.S. LLC, and Genzyme Corporation initiated an inter partes review ("IPR") in the United States Patent and Trademark Office ("USPTO") seeking a declaration of invalidity of the '487 Patent. On July 28 and 31, 2017, the same parties filed two additional IPR petitions in the USPTO seeking declarations of invalidity of the '487 Patent based on different grounds (the "Additional IPR Petitions"). On October 4, 2017, the Patent Trial and Appeal Board ("PTAB") of the USPTO issued a decision on the first IPR petition and declined to institute an IPR proceeding to review the validity of the '487 Patent. On February 15, 2018, the PTAB issued two decisions instituting the Company's and Sanofi's Additional IPR Petitions on all claims of the '487 Patent for which review had been requested. Oral hearings on the Additional IPR Petitions before the PTAB were held on November 14, 2018. On February 14, 2019, the PTAB issued final written decisions on the Additional IPR Petitions, invalidating all 17 claims of the '487 Patent as obvious based on one of the Additional IPR Petitions while declining to hold the challenged claims of the '487 Patent invalid based on the other. In April 2019, the parties filed notices of appeal with the Federal Circuit appealing the PTAB's respective adverse final written decisions on the Additional IPR Petitions, and oral argument has been scheduled for August 5, 2020. On April 5, 2017, Immunex Corporation filed a lawsuit against the Company, Sanofi, Sanofi-Aventis U.S. LLC, Genzyme Corporation, and Aventisub LLC in the United States District Court for the Central District of California seeking a judgment of patent infringement of the '487 Patent and a declaratory judgment of infringement of the '487 Patent, in each case by the Company's and the other defendants' Commercializing of Dupixent; monetary damages (together with interest); an order of willful infringement of the '487 Patent, which would allow the court in its discretion to award damages up to three times the amount assessed; costs and expenses of the lawsuit; and attorneys' fees. Immunex is not seeking an injunction in this proceeding at this time. On June 21, 2017, the court denied a motion to dismiss Immunex's complaint previously filed by the Company and the Sanofi parties. On June 28, 2017, the Company and the Sanofi parties filed an answer to Immunex's complaint and counterclaims against Immunex and Amgen (which was amended on October 31, 2017 to, among other things, add an inequitable conduct allegation), and Immunex and Amgen filed an answer to the counterclaims on July 28, 2017. A combined hearing on the construction of certain disputed claim terms of the '487 Patent and the Company and the Sanofi parties' motion for summary judgment on the issue of indefiniteness of the '487 Patent claims was held on July 12, 2018. On August 24, 2018, the court issued an order denying this motion and construed the disputed claim terms as proposed by Amgen. On February 28, 2019, the court granted a joint stipulation by the parties to stay the litigation pending resolution of the appeals of the PTAB's final written decisions on the Additional IPR Petitions discussed above. Europe On September 30, 2016, Sanofi initiated a revocation proceeding in the United Kingdom to invalidate the U.K. counterpart of European Patent No. 2,292,665 (the "'665 Patent"), another patent owned by Immunex relating to antibodies that bind the human interleukin-4 receptor. At the joint request of the parties to the revocation proceeding, the U.K. Patents Court ordered on January 30, 2017 that the revocation action be stayed pending the final determination of the currently pending EPO opposition proceedings initiated by the Company and Sanofi in relation to the '665 Patent. The oral hearing before the EPO on the oppositions occurred on November 20, 2017, at which the claims of the '665 Patent were found invalid and the patent was revoked. A final written decision of revocation of the '665 Patent was issued by the EPO on January 4, 2018. Immunex filed a notice of appeal of the EPO's decision on January 31, 2018. On September 20, 2017 and September 21, 2017, respectively, the Company and Sanofi initiated opposition proceedings in the EPO against Immunex's European Patent No. 2,990,420 (the "'420 Patent"), a divisional patent of the '665 Patent (i.e., a patent that shares the same priority date, disclosure, and patent term of the parent '665 Patent but contains claims to a different invention). The oral hearing before the EPO on the oppositions occurred on February 14–15, 2019, at which the '420 Patent was revoked in its entirety. Immunex filed a notice of appeal of the EPO's decision on May 31, 2019. The original patent term of the Immunex patents is set to expire in 2021. Department of Justice Investigations In January 2017, the Company received a subpoena from the U.S. Attorney's Office for the District of Massachusetts requesting documents relating to its support of 501(c)(3) organizations that provide financial assistance to patients; documents concerning its provision of financial assistance to patients with respect to products sold or developed by Regeneron (including EYLEA, Praluent, ARCALYST, and ZALTRAP^®); and certain other related documents and communications. On June 24, 2020, the U.S. Attorney's Office for the District of Massachusetts filed a civil complaint in the U.S. District Court for the District of Massachusetts alleging violations of the federal Anti-Kickback Statute, and asserting causes of action under the federal False Claims Act and state law. In September 2019, the Company and Regeneron Healthcare Solutions, Inc., a wholly-owned subsidiary of the Company, each received a civil investigative demand ("CID") from the U.S. Department of Justice pursuant to the federal False Claims Act relating to remuneration paid to physicians in the form of consulting fees, advisory boards, speaker fees, and payment or reimbursement for travel and entertainment allegedly in violation of the federal Anti-Kickback Statute. The CIDs relate to EYLEA, Praluent, Dupixent, ZALTRAP, ARCALYST, and Kevzara and cover the period from January 2015 to the present. The Company is cooperating with this investigation. Proceedings Relating to EYLEA (aflibercept) Injection Pre-filled Syringe On June 19, 2020, Novartis Pharma AG, Novartis Pharmaceuticals Corporation, and Novartis Technology LLC (collectively, "Novartis") filed a complaint with the U.S. International Trade Commission (the "ITC") pursuant to Section 337 of the Tariff Act of 1930 requesting that the ITC institute an investigation relating to the importation into the United States and/or sale within the United States after importation of EYLEA pre-filled syringes ("PFS") and/or components thereof which allegedly infringe Novartis’s U.S. Patent No. 9,220,631 (the "'631 Patent"). Novartis also requested a permanent limited exclusion order forbidding entry into the United States of EYLEA PFS or components thereof; a permanent cease-and-desist order from the importation, sale, offer for sale, advertising, packaging, or solicitation of any sale by the Company of EYLEA PFS or components thereof; and a bond should the Company continue to import EYLEA PFS (if found to infringe) during, if applicable, any 60-day Presidential review period (i.e., the period when the President of the United States (or his designee) can disapprove any ITC decision to issue an exclusion order or cease-and-desist order). On June 19, 2020, Novartis also filed a patent infringement lawsuit in the U.S. District Court for the Northern District of New York asserting claims of the '631 Patent and seeking preliminary and permanent injunctions to prevent the Company from continuing to infringe the '631 Patent. Novartis also seeks a judgment of patent infringement of the '631 Patent, monetary damages (together with interest), treble damages, costs and expenses of the lawsuits, and attorneys' fees. On July 30, 2020, the court granted the Company's motion to stay these proceedings until a determination in the ITC proceedings discussed above, including any appeals therefrom, becomes final. On July 16, 2020, the Company initiated two IPR petitions in the USPTO seeking a declaration of invalidity of the '631 Patent on two separate grounds. On July 17, 2020, the Company filed an antitrust lawsuit against Novartis and Vetter Pharma International Gmbh in the United States District Court for the Southern District of New York seeking a declaration that the '631 Patent is unenforceable and a judgment that the defendants' conduct violates Sections 1 and 2 of the Sherman Antitrust Act of 1890, as amended. The Company is also seeking injunctive relief and treble damages. Proceedings Relating to fasinumab On May 21, 2020, the Company and Teva Pharmaceutical Industries Limited filed a lawsuit against Rinat Neurosciences Corp. ("Rinat"), a wholly owned subsidiary of Pfizer Inc., in the English High Court of Justice in London, seeking invalidation and revocation of Rinat's European Patent No. 2,270,048 (the "'048 Patent"), European Patent No. 1,871,416 (the "'416 Patent"), and European Patent No. 2,305,711 (the "'711 Patent"), each of which pertains to the use of NGF monoclonal antibodies to treat certain symptoms in patients suffering from osteoarthritis. On July 21, 2020, Rinat filed its defense and counterclaim seeking a declaration of infringement of the '048 Patent by fasinumab. The counterclaim also seeks a permanent injunction, damages, an accounting of profits, and costs and interest. A trial has been scheduled to commence in late November or early December 2021.

Interim Financial Statements (Policies)

6 Months Ended

Jun. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

Basis of PresentationThe interim Condensed Consolidated Financial Statements of Regeneron Pharmaceuticals, Inc. and its subsidiaries ("Regeneron," "Company," "we," "us," and "our") 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 condensed consolidated financial statements for such periods. The results of operations for any interim period are not necessarily indicative of the results for the full year. The December 31, 2019 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, 2019.

Use of Estimates

Recently Adopted Accounting Standards

Collaboration Agreements


Nature/Type of Payment						Statement of Operations Presentation
Regeneron's share of profits or losses in connection with commercialization of products						Collaboration revenue
Reimbursement for manufacturing of commercial supplies						Collaboration revenue
Royalties and/or sales-based milestones earned						Collaboration revenue
Reimbursement of Regeneron's research and development expenses						Reduction to Research and development expenses
Regeneron's obligation for its share of collaborator's research and development expenses						Research and development expense
Up-front and development milestone payments to collaborator						Research and development expense
Reimbursement of Regeneron's commercialization-related expenses						Reduction to Selling, general, and administrative expense
Regeneron's obligation for its share of collaborator's commercialization-related expenses						Selling, general, and administrative expense
Regeneron's obligation to pay collaborator for its share of gross profits when Regeneron is deemed to be the principal						Cost of goods sold
Up-front and development milestones earned (when we have a combined unit of account which includes a license and providing research and development services)						Other operating income

•receive royalties and/or sales-based milestone payments from our collaborator, we recognize such amounts in the period earned.

Legal Matters

Costs associated with the Company's involvement in legal proceedings are expensed as incurred.

- Definition

Disclosure of accounting policy for revenue from contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130561-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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+ Details

Interim Financial Statements (Tables)

6 Months Ended

Jun. 30, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Reclassifications

The tables below present the impact of the change on the Company’s previously-filed Consolidated Balance Sheet as of December 31, 2019, the Condensed Consolidated Statement of Operations for the three and six months ended June 30, 2019, and the Condensed Consolidated Statement of Cash Flows for the six months ended June 30, 2019. The Company’s previously-filed balance sheet has been updated to reflect the addition of the caption Other liabilities for the presentation of up-front and development milestones paid by collaborators that are deferred. There was no impact on the Company’s previously-filed Consolidated Statements of Stockholders’ Equity.


	December 31, 2019
Balance Sheet Data:	As Previously Reported		Adjustments		As Revised
Accrued expenses and other current liabilities	$	1,086.8	$	124.6	$	1,211.4
Deferred revenue - Sanofi (current)	$	395.5	$	(85.0)	$	310.5
Deferred revenue - other (current)	$	196.2	$	(124.6)	$	71.6
Other liabilities - Sanofi (current)	—		$	85.0	$	85.0
Deferred revenue - Sanofi (noncurrent)	$	509.7	$	(482.0)	$	27.7
Deferred revenue - other (noncurrent)	$	109.3	$	(31.7)	$	77.6
Other liabilities - Sanofi (noncurrent)	—		$	482.0	$	482.0
Other noncurrent liabilities	$	286.0	$	31.7	$	317.7


	Three Months Ended June 30, 2019										Six Months Ended June 30, 2019
Statement of Operations Data:	As Previously Reported		Adjustments		As Revised		As Previously Reported		Adjustments		As Revised
Sanofi collaboration revenue	$	349.1	$	(273.3)	$	75.8	$	595.5	$	(537.7)	$	57.8
Bayer collaboration revenue	$	289.0	$	(11.8)	$	277.2	$	565.2	$	(24.0)	$	541.2
Other revenue	$	90.3	$	(70.8)	$	19.5	$	175.1	$	(133.4)	$	41.7
Total revenues	$	1,933.7	$	(355.9)	$	1,577.8	$	3,645.5	$	(695.1)	$	2,950.4

Research and development	$	1,048.3	$	(162.8)	$	885.5	$	1,690.1	$	(318.5)	$	1,371.6
Selling, general, and administrative	$	417.3	$	(122.7)	$	294.6	$	828.1	$	(242.4)	$	585.7
Cost of collaboration and contract manufacturing⁽¹⁾	$	85.5	$	(6.7)	$	78.8	$	193.8	$	(13.8)	$	180.0
Other operating (income) expense, net	—		$	(63.7)	$	(63.7)	—		$	(120.4)	$	(120.4)
Total operating expenses	$	1,618.1	$	(355.9)	$	1,262.2	$	2,849.9	$	(695.1)	$	2,154.8

⁽¹⁾ In addition to the reclassification of certain amounts in connection with the change in accounting presentation described above, the Company also reclassified certain immaterial reimbursements that were previously classified as collaboration revenue to Cost of collaboration and contract manufacturing.


	Six Months Ended June 30, 2019
Cash Flows Data:	As Previously Reported		Adjustments		As Revised
Cash flows from operating activities:
Increase in deferred revenue	$	401.1	$	(271.3)	$	129.8
Increase in accounts payable, accrued expenses, and other liabilities	$	110.3	$	271.3	$	381.6

Product Sales (Tables)

6 Months Ended

Jun. 30, 2020

Revenues [Abstract]

Schedule of product sales

Net product sales consist of the following:


	Three Months Ended June 30,							Six Months Ended June 30,
Net Product Sales in the United States	2020		2019		2020			2019
EYLEA^®	$	1,113.7	$	1,160.3	$	2,285.7		$	2,234.4
Libtayo^®	63.3		40.8		125.0			67.6
Praluent^®	47.2		*		47.2		*	*
ARCALYST^®	2.7		4.2		5.7			7.7
	$	1,226.9	$	1,205.3	$	2,463.6		$	2,309.7

^* Effective April 1, 2020, the Company is solely responsible for the development and commercialization of Praluent in the United States and records net product sales of Praluent in the United States. See Note 3 for further details.

Schedules of Concentration of Risk, by Risk Factor

Sales to each of these customers as a percentage of the Company's total gross product revenue are as follows:


	Three Months Ended June 30,						Six Months Ended June 30,
	2020		2019		2020		2019
Besse Medical, a subsidiary of AmerisourceBergen Corporation	53	%	56	%	53	%	57	%
McKesson Corporation	32	%	34	%	34	%	32	%

Collaboration, License, and Other Agreements (Tables)

6 Months Ended

Jun. 30, 2020

Revenue from Contract with Customer [Abstract]

Schedule of collaboration revenue


Nature/Type of Payment						Statement of Operations Presentation
Regeneron's share of profits or losses in connection with commercialization of products						Collaboration revenue
Reimbursement for manufacturing of commercial supplies						Collaboration revenue
Royalties and/or sales-based milestones earned						Collaboration revenue
Reimbursement of Regeneron's research and development expenses						Reduction to Research and development expenses
Regeneron's obligation for its share of collaborator's research and development expenses						Research and development expense
Up-front and development milestone payments to collaborator						Research and development expense
Reimbursement of Regeneron's commercialization-related expenses						Reduction to Selling, general, and administrative expense
Regeneron's obligation for its share of collaborator's commercialization-related expenses						Selling, general, and administrative expense
Regeneron's obligation to pay collaborator for its share of gross profits when Regeneron is deemed to be the principal						Cost of goods sold
Up-front and development milestones earned (when we have a combined unit of account which includes a license and providing research and development services)						Other operating income

Amounts recognized in our Statements of Operations in connection with our collaborations with Sanofi are detailed below:


	Statement of Operations Classification	Three Months Ended June 30,									Six Months Ended June 30,
				2020			2019			2020			2019
Antibody:
Regeneron's share of profits in connection with commercialization of antibodies	Sanofi collaboration revenue	$	171.9		$	38.8		$	342.8		$	11.0
Reimbursement for manufacturing of commercial supplies	Sanofi collaboration revenue	$	100.6		$	43.9		$	180.7		$	58.4
Reimbursement of research and development expenses	Reduction of Research and development expense	$	51.3		$	81.8		$	128.9		$	156.3
Regeneron's obligation for its share of Sanofi research and development expenses	Research and development expense	$	(24.9)		$	(12.2)		$	(41.6)		$	(19.6)
Reimbursement of commercialization-related expenses	Reduction of Selling, general, and administrative expense	$	86.0		$	121.1		$	177.2		$	237.7

Immuno-oncology:
Regeneron's share of losses in connection with commercialization of Libtayo outside the United States	Sanofi collaboration revenue	$	(6.4)		$	(6.9)		$	(12.6)		$	(11.6)
Reimbursement for manufacturing of commercial supplies	Sanofi collaboration revenue	$	3.0		—			$	5.1		—
Reimbursement of research and development expenses	Reduction of Research and development expense	$	47.0		$	36.5		$	86.9		$	82.9
Reimbursement of commercialization-related expenses	Reduction of Selling, general, and administrative expense	$	14.3		$	1.8		$	24.7		$	4.0
Regeneron's obligation for Sanofi's share of Libtayo U.S. gross profits	Cost of goods sold	$	(28.2)		$	(19.0)		$	(55.0)		$	(31.4)
Amounts recognized in connection with up-front payments received	Other operating income	$	20.5		$	29.0		$	37.0		$	55.3

Amounts recognized in our Statements of Operations in connection with our Bayer EYLEA collaboration are as follows:


	Statement of Operations Classification	Three Months Ended June 30,									Six Months Ended June 30,
				2020			2019			2020			2019
Regeneron's net profit in connection with commercialization of EYLEA outside the United States	Bayer collaboration revenue	$	230.9		$	269.0		$	484.7		$	518.3
Reimbursement for manufacturing of commercial supplies	Bayer collaboration revenue	$	13.3		$	8.2		$	40.9		$	22.9
Reimbursement of development expenses	Reduction of Research and development expense	$	10.8		$	8.0		$	22.8		$	10.6
Regeneron's obligation for its share of Bayer research and development expenses	Research and development expense	$	(5.3)		$	(2.0)		$	(13.4)		$	(6.6)
Reimbursement of other expenses	Cost of collaboration and contract manufacturing	$	1.6		$	4.1		$	3.3		$	12.9

Amounts recognized in our Statements of Operations in connection with the Teva Collaboration Agreement are as follows:


	Statement of Operations Classification	Three Months Ended June 30,									Six Months Ended June 30,
				2020			2019			2020			2019
Reimbursement of research and development expenses	Reduction of Research and development expense	$	31.0		$	36.5		$	56.2		$	68.7
Amounts recognized in connection with up-front and development milestone payments received	Other operating income	$	20.7		$	24.5		$	37.3		$	46.0

Summary of contract balances

The following table summarizes contract balances in connection with the Company's Antibody Collaboration with Sanofi:


	June 30,		December 31,
	2020		2019
Accounts receivable	$	383.1	$	272.7
Deferred revenue	$	405.5	$	328.8

The following table summarizes contract balances in connection with the Company's IO Collaboration with Sanofi:


	June 30,		December 31,
	2020		2019
Accounts receivable, net	$	(2.2)	$	(16.7)
Deferred revenue	$	12.5	$	9.4
Other liabilities	$	486.7	$	558.6

The following table summarizes contract balances in connection with our Bayer EYLEA collaboration:


	June 30,		December 31,
	2020		2019
Accounts receivable - other	$	245.8	$	311.6
Deferred revenue	$	125.3	$	123.0

The following table summarizes contract balances in connection with the Teva Collaboration Agreement:


	June 30,		December 31,
	2020		2019
Accounts receivable - other	$	28.5	$	21.2
Other liabilities	$	77.9	$	114.4

Net Income Per Share (Tables)

6 Months Ended

Jun. 30, 2020

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 June 30,						Six Months Ended June 30,
	2020		2019		2020		2019
Net income - basic and diluted	$	897.3	$	193.1	$	1,521.9	$	654.2

(Shares in millions)
Weighted average shares - basic	109.6		109.2		109.7		109.1
Effect of dilutive securities:
Stock options	7.8		5.4		6.7		5.9
Restricted stock	0.5		—		0.4		—
Weighted average shares - diluted	117.9		114.6		116.8		115.0

Net income per share - basic	$	8.19	$	1.77	$	13.87	$	6.00
Net income per share - diluted	$	7.61	$	1.68	$	13.03	$	5.69

Antidilutive Securities

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


	Three Months Ended June 30,			Six Months Ended June 30,
(Shares in millions)	2020	2019	2020	2019
Stock options	0.1	18.3	3.5	18.1
Restricted stock	—	0.4	—	—

Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Available-for-sale Debt Securities

The following tables summarize the Company's investments in available-for-sale debt securities:


	Amortized		Unrealized						Fair
As of June 30, 2020	Cost Basis		Gains		Losses		Value
Corporate bonds	$	2,393.2	$	41.9	$	(0.7)	$	2,434.4
U.S. government and government agency obligations	81.6		1.1		—		82.7
Sovereign bonds	27.0		1.2		—		28.2
Commercial paper	283.1		0.6		—		283.7
Certificates of deposit	105.4		0.1		—		105.5
	$	2,890.3	$	44.9	$	(0.7)	$	2,934.5

As of December 31, 2019
Corporate bonds	$	3,960.5	$	27.8	$	(0.2)	$	3,988.1
U.S. government and government agency obligations	54.3		0.2		(0.1)		54.4
Sovereign bonds	26.9		0.4		—		27.3
Commercial paper	92.3		—		—		92.3
Certificates of deposit	72.3		0.1		—		72.4
	$	4,206.3	$	28.5	$	(0.3)	$	4,234.5

Marketable Securities, Based on Contractual Maturity Dates

The fair values of available-for-sale debt security investments by contractual maturity consist of the following:


	June 30,		December 31,
	2020		2019
Maturities within one year	$	1,152.0	$	1,596.5
Maturities after one year through five years	1,779.6		2,638.0
Maturities after five years	2.9		—
	$	2,934.5	$	4,234.5

Fair Value and Unrealized Losses of Marketable Securities


	Less than 12 Months					12 Months or Greater					Total
As of June 30, 2020	Fair Value		Unrealized Loss		Fair Value	Unrealized Loss	Fair Value		Unrealized Loss
Corporate bonds	$	247.9	$	(0.7)	—	—	$	247.9	$	(0.7)

As of December 31, 2019
Corporate bonds	$	257.2	$	(0.2)	—	—	$	257.2	$	(0.2)
U.S. government and government agency obligations	17.3		(0.1)		—	—	17.3		(0.1)
	$	274.5	$	(0.3)	—	—	$	274.5	$	(0.3)

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Schedule of assets measured at fair value on a recurring basis

•Level 1 - Quoted prices in active markets for identical assets

•Level 3 - Significant other unobservable inputs


			Fair Value Measurements at Reporting Date
As of June 30, 2020	Fair Value		Level 1		Level 2
Available-for-sale debt securities:
Corporate bonds	$	2,434.4	—		$	2,434.4
U.S. government and government agency obligations	82.7		—		82.7
Sovereign bonds	28.2		—		28.2
Commercial paper	283.7		—		283.7
Certificates of deposit	105.5		—		105.5
Equity securities (unrestricted)	37.8		$	37.8	—
Equity securities (restricted)	767.3		751.9		15.4
	$	3,739.6	$	789.7	$	2,949.9

As of December 31, 2019
Available-for-sale debt securities:
Corporate bonds	$	3,988.1	—		$	3,988.1
U.S. government and government agency obligations	54.4		—		54.4
Sovereign bonds	27.3		—		27.3
Commercial paper	92.3		—		92.3
Certificates of deposit	72.4		—		72.4
Equity securities (unrestricted)	61.6		$	61.6	—
Equity securities (restricted)	557.2		557.2		—
	$	4,853.3	$	618.8	$	4,234.5

Inventories (Tables)

6 Months Ended

Jun. 30, 2020

Inventory Disclosure [Abstract]

Schedule of Inventory, Current

Inventories consist of the following:


	June 30,		December 31,
	2020		2019
Raw materials	$	306.3	$	216.3
Work-in-process	696.9		727.7
Finished goods	132.0		70.6
Deferred costs	505.7		400.9
	$	1,640.9	$	1,415.5

Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Schedule of Shares Repurchased


	Six Months Ended June 30, 2020
Number of shares repurchased	719,167
Total cost of shares received	$	272.8

As of June 30, 2020, the Company had $473.1 million which remained available for share repurchases under the program.

The table below summarizes the shares of our Common Stock Sanofi elected to sell, and we elected to purchase, to satisfy Sanofi's funding obligations and the cost of the shares received, which were recorded as Treasury Stock:


	Three Months Ended June 30,					Six Months Ended June 30,
	2020		2019	2020		2019
Libtayo:
Number of shares purchased (by issuing a credit towards the amount owed by Sanofi)	34,050		—	77,677		106,972
Total cost of shares received	$	20.3	—	$	41.7	$	44.0

Dupilumab/REGN3500:
Number of shares purchased (in cash)	86,184		—	171,471		24,143
Total cost of shares received	$	51.5	—	$	93.3	$	10.0

Statement of Cash Flows (Tables)

6 Months Ended

Jun. 30, 2020

Supplemental Cash Flow Information [Abstract]

Schedule of Cash and Cash Equivalents


	June 30,		June 30,
	2020		2019
Cash and cash equivalents	$	1,992.2	$	1,045.5
Restricted cash included in Other noncurrent assets	12.5		12.5
Total cash, cash equivalents, and restricted cash shown in the Condensed Consolidated Statement of Cash Flows	$	2,004.7	$	1,058.0

Restrictions on Cash and Cash Equivalents


	June 30,		June 30,
	2020		2019
Cash and cash equivalents	$	1,992.2	$	1,045.5
Restricted cash included in Other noncurrent assets	12.5		12.5
Total cash, cash equivalents, and restricted cash shown in the Condensed Consolidated Statement of Cash Flows	$	2,004.7	$	1,058.0

Interim Financial Statements - Schedule of Balance Sheet Data (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued expenses and other current liabilities	$ 1,257.0	$ 1,211.4
Other liabilities - Sanofi	103.8	85.0
Other noncurrent liabilities	457.9	317.7
Sanofi
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, current	380.2	310.5
Deferred revenue, noncurrent	37.8	27.7
Other noncurrent liabilities	390.3	482.0
Other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, current	81.3	71.6
Deferred revenue, noncurrent	$ 67.0	77.6
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued expenses and other current liabilities		1,086.8
Other liabilities - Sanofi		0.0
Other noncurrent liabilities		286.0
As Previously Reported \| Sanofi
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, current		395.5
Deferred revenue, noncurrent		509.7
Other noncurrent liabilities		0.0
As Previously Reported \| Other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, current		196.2
Deferred revenue, noncurrent		109.3
Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accrued expenses and other current liabilities		124.6
Other liabilities - Sanofi		85.0
Other noncurrent liabilities		31.7
Adjustments \| Sanofi
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, current		(85.0)
Deferred revenue, noncurrent		(482.0)
Other noncurrent liabilities		482.0
Adjustments \| Other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue, current		(124.6)
Deferred revenue, noncurrent		$ (31.7)

Interim Financial Statements - Schedule of Statements of Operations Data (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 1,952.0	$ 1,577.8	$ 3,780.2	$ 2,950.4
Research and development	722.0	885.5	1,305.9	1,371.6
Selling, general, and administrative	348.3	294.6	715.6	585.7
Other operating (income) expense, net	(50.2)	(63.7)	(90.6)	(120.4)
Total operating expenses	1,295.6	1,262.2	2,423.7	2,154.8
Collaboration and contract manufacturing
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold	173.0	78.8	311.5	180.0
Sanofi \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	269.1	75.8	516.0	57.8
Bayer \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	244.2	277.2	525.6	541.2
Other \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 211.8	19.5	$ 275.0	41.7
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		1,933.7		3,645.5
Research and development		1,048.3		1,690.1
Selling, general, and administrative		417.3		828.1
Other operating (income) expense, net		0.0		0.0
Total operating expenses		1,618.1		2,849.9
As Previously Reported \| Collaboration and contract manufacturing
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold		85.5		193.8
As Previously Reported \| Sanofi \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		349.1		595.5
As Previously Reported \| Bayer \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		289.0		565.2
As Previously Reported \| Other \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		90.3		175.1
Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		(355.9)		(695.1)
Research and development		(162.8)		(318.5)
Selling, general, and administrative		(122.7)		(242.4)
Other operating (income) expense, net		(63.7)		(120.4)
Total operating expenses		(355.9)		(695.1)
Adjustments \| Collaboration and contract manufacturing
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold		(6.7)		(13.8)
Adjustments \| Sanofi \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		(273.3)		(537.7)
Adjustments \| Bayer \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		(11.8)		(24.0)
Adjustments \| Other \| Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues		$ (70.8)		$ (133.4)

Interim Financial Statements - Schedule of Cash Flows Data (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in deferred revenue	$ 78.9	$ 129.8
Increase in accounts payable, accrued expenses, and other liabilities	$ 20.9	381.6
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in deferred revenue		401.1
Increase in accounts payable, accrued expenses, and other liabilities		110.3
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase in deferred revenue		(271.3)
Increase in accounts payable, accrued expenses, and other liabilities		$ 271.3

Product Sales - Schedule of Net Product Sales (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 1,952.0	$ 1,577.8	$ 3,780.2	$ 2,950.4
Product
Disaggregation of Revenue [Line Items]
Revenues	1,226.9	1,205.3	2,463.6	2,309.7
UNITED STATES \| EYLEA
Disaggregation of Revenue [Line Items]
Revenues	1,113.7	1,160.3	2,285.7	2,234.4
UNITED STATES \| Libtayo
Disaggregation of Revenue [Line Items]
Revenues	63.3	40.8	125.0	67.6
UNITED STATES \| Praluent
Disaggregation of Revenue [Line Items]
Revenues	47.2		47.2
UNITED STATES \| ARCALYST
Disaggregation of Revenue [Line Items]
Revenues	2.7	4.2	5.7	7.7
UNITED STATES \| Product
Disaggregation of Revenue [Line Items]
Revenues	$ 1,226.9	$ 1,205.3	$ 2,463.6	$ 2,309.7

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Product Sales - Schedule of Concentration of Risk, by Risk Factor (Details) - Gross Sales Revenue - Customer concentration risk	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Besse Medical, a subsidiary of AmerisourceBergen Corporation
Concentration Risk [Line Items]
Concentration risk, percentage	53.00%	56.00%	53.00%	57.00%
McKesson Corporation
Concentration Risk [Line Items]
Concentration risk, percentage	32.00%	34.00%	34.00%	32.00%

Collaboration, License, and Other Agreements - Sanofi, Antibody Narrative (Details) - USD ($)		3 Months Ended	6 Months Ended
	Apr. 01, 2020	Jun. 30, 2020	Jun. 30, 2020
Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Percentage of Trial Costs borne by collaborating party			80.00%
Percentage of Trial Costs borne by entity			20.00%
Maximum amount of sales milestone payments if total sales achieve specific levels			$ 250,000,000.0
Levels of twelve month sales at which sales milestone payments would be received			$ 1,000,000,000.0
Period for achieving sales target for milestone payment, rolling basis			12 months
Praluent Agreement
Disaggregation of Revenue [Line Items]
Royalty percentage to be received on net product sales outside of the United States	5.00%
Percentage of damages company is responsible for		50.00%
Sanofi \| Praluent Agreement
Disaggregation of Revenue [Line Items]
Percentage of royalty payment that can be used to offset litigation proceedings		50.00%

Collaboration, License, and Other Agreements - Amounts Recognized In Statement of Operations with Sanofi (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 1,952.0	$ 1,577.8	$ 3,780.2	$ 2,950.4
Research and development expense	(722.0)	(885.5)	(1,305.9)	(1,371.6)
Regeneron's share of profits in connection with commercialization of antibodies \| Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Revenues	171.9	38.8	342.8	11.0
Reimbursement for manufacturing of commercial supplies \| Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Revenues	100.6	43.9	180.7	58.4
Reimbursement for manufacturing of commercial supplies \| Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Revenues	3.0	0.0	5.1	0.0
Reimbursement of research and development expenses \| Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Reduction of Research and development expense	51.3	81.8	128.9	156.3
Reimbursement of research and development expenses \| Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Reduction of Research and development expense	47.0	36.5	86.9	82.9
Regeneron's obligation for its share of Sanofi research and development expenses \| Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Research and development expense	(24.9)	(12.2)	(41.6)	(19.6)
Reimbursement of commercialization-related expenses \| Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Reduction of Selling, general, and administrative expense	86.0	121.1	177.2	237.7
Reimbursement of commercialization-related expenses \| Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Reduction of Selling, general, and administrative expense	14.3	1.8	24.7	4.0
Regeneron's obligation for Sanofi's share of Libtayo U.S. gross profits \| Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Cost of goods sold	(28.2)	(19.0)	(55.0)	(31.4)
Amounts recognized in connection with up-front payments received \| Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Other operating income	20.5	29.0	37.0	55.3
Outside United States \| Regeneron's share of profits in connection with commercialization of antibodies \| Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Revenues	$ (6.4)	$ (6.9)	$ (12.6)	$ (11.6)

Collaboration, License, and Other Agreements - Schedule of Contract Balances, Antibody Collaboration (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Accounts receivable, net	$ 389.2	$ 260.6
Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
Accounts receivable, net	383.1	272.7
Deferred revenue	$ 405.5	$ 328.8

Collaboration, License, and Other Agreements - Sanofi, Immuno-Oncology Narrative (Details) - Sanofi Collaboration Agreement, Immuno-oncology $ in Millions	Jun. 30, 2020 USD ($) shares
Disaggregation of Revenue [Line Items]
Maximum shares the collaborator could sell (in shares) \| shares	279,766
Unsatisfied obligation \| $	$ 1,020

Collaboration, License, and Other Agreements - Schedule of Contract Balances, IO Collaboration (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Accounts receivable, net	$ (389.2)	$ (260.6)
Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Accounts receivable, net	(2.2)	(16.7)
Deferred revenue	12.5	9.4
Other liabilities	$ 486.7	$ 558.6

Collaboration Agreements - Amounts Recognized in Statement of Operations with Bayer (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 1,952.0	$ 1,577.8	$ 3,780.2	$ 2,950.4
Research and development expense	(722.0)	(885.5)	(1,305.9)	(1,371.6)
Bayer \| Product and service, other
Disaggregation of Revenue [Line Items]
Revenues	244.2	277.2	525.6	541.2
Outside United States \| Bayer \| Regeneron's net profit in connection with commercialization of EYLEA outside the United States
Disaggregation of Revenue [Line Items]
Revenues	230.9	269.0	484.7	518.3
Outside United States \| Bayer \| Reimbursement for manufacturing of commercial supplies
Disaggregation of Revenue [Line Items]
Revenues	13.3	8.2	40.9	22.9
Outside United States \| Bayer \| Reimbursement of development expenses
Disaggregation of Revenue [Line Items]
Reduction of Research and development expense	10.8	8.0	22.8	10.6
Outside United States \| Bayer \| Regeneron's obligation for its share of Bayer research and development expenses
Disaggregation of Revenue [Line Items]
Research and development expense	(5.3)	(2.0)	(13.4)	(6.6)
Outside United States \| Bayer \| Reimbursement of other expenses
Disaggregation of Revenue [Line Items]
Cost of collaboration and contract manufacturing	$ 1.6	$ 4.1	$ 3.3	$ 12.9

Collaboration, License, and Other Agreements - Bayer Narrative (Details) - Bayer	6 Months Ended
	Jun. 30, 2020
Minimum
Disaggregation of Revenue [Line Items]
Revenue based on percentage of annual sales in Japan	33.50%
Maximum
Disaggregation of Revenue [Line Items]
Revenue based on percentage of annual sales in Japan	40.00%

Collaboration, License, and Other Agreements - Schedule of Contract Balances, Bayer Collaboration (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Accounts receivable - other	$ 431.1	$ 425.0
Bayer
Disaggregation of Revenue [Line Items]
Accounts receivable - other	245.8	311.6
Deferred revenue	$ 125.3	$ 123.0

Collaboration, License, and Other Agreements - Amounts Recognized in Statement of Operations with Teva (Details) - Teva - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reimbursement of research and development expenses
Disaggregation of Revenue [Line Items]
Reduction of Research and development expense	$ 31.0	$ 36.5	$ 56.2	$ 68.7
Amounts recognized in connection with up-front and development milestone payments received
Disaggregation of Revenue [Line Items]
Other operating income	$ 20.7	$ 24.5	$ 37.3	$ 46.0

Collaboration, License, and Other Agreements - Schedule of Contract Balances, Teva Collaboration (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Accounts receivable - other	$ 431.1	$ 425.0
Teva
Disaggregation of Revenue [Line Items]
Accounts receivable - other	28.5	21.2
Other liabilities	$ 77.9	$ 114.4

Collaboration, License, and Other Agreements - Teva Narrative (Details) $ in Millions	Jun. 30, 2020 USD ($)
Teva
Disaggregation of Revenue [Line Items]
Unsatisfied obligation	$ 173.3

Collaboration, License, and Other Agreements - Intellia Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	May 31, 2020
Research Collaboration and Licensing Arrangements [Line Items]
Research and development	$ 722.0	$ 885.5	$ 1,305.9	$ 1,371.6
Intellia
Research Collaboration and Licensing Arrangements [Line Items]
Upfront payment made for collaboration agreement	70.0
Research and development	$ 15.0
Intellia \| Common Stock
Research Collaboration and Licensing Arrangements [Line Items]
Shares purchased (in shares)					925,218
Shares purchase price					$ 30.0

Collaboration, License, and Other Agreements - BARDA Narrative (Details) - Other Transaction Agreement - USD ($) $ in Millions	6 Months Ended
	Dec. 31, 2020	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Percentage of research and development costs to be paid by counterparty		80.00%
Scenario, Forecast
Disaggregation of Revenue [Line Items]
Maximum agreement payments	$ 450.2

Net Income Per Share - Schedule of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income - basic and diluted	$ 897.3	$ 624.6	$ 193.1	$ 461.1	$ 1,521.9	$ 654.2
Weighted average shares outstanding - basic (in shares)	109.6		109.2		109.7	109.1
Weighted average shares - diluted (in shares)	117.9		114.6		116.8	115.0
Net income per share - basic (in dollars per share)	$ 8.19		$ 1.77		$ 13.87	$ 6.00
Net income per share - diluted (in dollars per share)	$ 7.61		$ 1.68		$ 13.03	$ 5.69
Stock options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities (in shares)	7.8		5.4		6.7	5.9
Restricted stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities (in shares)	0.5		0.0		0.4	0.0

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

Net Income Per Share - Schedule of Antidilutive Securities Excluded From Computation (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares (in shares)	0.1	18.3	3.5	18.1
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average number of shares (in shares)	0.0	0.4	0.0	0.0

Marketable Securities - Schedule of Investments in Available For Sale Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	$ 2,890.3	$ 4,206.3
Unrealized Gains	44.9	28.5
Unrealized Losses	(0.7)	(0.3)
Fair Value	2,934.5	4,234.5
Corporate bonds \| Unrestricted
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	2,393.2	3,960.5
Unrealized Gains	41.9	27.8
Unrealized Losses	(0.7)	(0.2)
Fair Value	2,434.4	3,988.1
U.S. government and government agency obligations \| Unrestricted
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	81.6	54.3
Unrealized Gains	1.1	0.2
Unrealized Losses	0.0	(0.1)
Fair Value	82.7	54.4
Sovereign bonds \| Unrestricted
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	27.0	26.9
Unrealized Gains	1.2	0.4
Unrealized Losses	0.0	0.0
Fair Value	28.2	27.3
Commercial paper \| Unrestricted
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	283.1	92.3
Unrealized Gains	0.6	0.0
Unrealized Losses	0.0	0.0
Fair Value	283.7	92.3
Certificates of deposit \| Unrestricted
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	105.4	72.3
Unrealized Gains	0.1	0.1
Unrealized Losses	0.0	0.0
Fair Value	$ 105.5	$ 72.4

Marketable Securities - Schedule of Debt Securities Based on Contractual Maturity Dates (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Maturities within one year	$ 1,152.0	$ 1,596.5
Maturities after one year through five years	1,779.6	2,638.0
Maturities after five years	2.9	0.0
Total	$ 2,934.5	$ 4,234.5

Marketable Securities - Schedule of Fair Value and Unrealized Losses of Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months		$ 274.5
Unrealized Loss - Less than 12 months		(0.3)
Fair Value - 12 Months or Greater		0.0
Unrealized Loss - 12 Months or Greater		0.0
Fair Value - Total		274.5
Unrealized Loss - Total		(0.3)
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months	$ 247.9	257.2
Unrealized Loss - Less than 12 months	(0.7)	(0.2)
Fair Value - 12 Months or Greater	0.0	0.0
Unrealized Loss - 12 Months or Greater	0.0	0.0
Fair Value - Total	247.9	257.2
Unrealized Loss - Total	$ (0.7)	(0.2)
U.S. government and government agency obligations
Debt Securities, Available-for-sale [Line Items]
Fair Value - Less than 12 Months		17.3
Unrealized Loss - Less than 12 months		(0.1)
Fair Value - 12 Months or Greater		0.0
Unrealized Loss - 12 Months or Greater		0.0
Fair Value - Total		17.3
Unrealized Loss - Total		$ (0.1)

Marketable Securities - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
Marketable Securities - Narrative (Details) - USD ($)	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Realized gain (loss) on sales of marketable securities	$ 28,000,000.0	$ 0	$ 28,300,000	$ 0

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Net unrealized gain (loss) on securities	$ 228.1	$ (116.9)	$ 171.3	$ (74.1)
Securities owned not readily marketable	$ 70.6		$ 70.6		$ 55.6

Inventories - Schedule of Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 306.3	$ 216.3
Work-in-process	696.9	727.7
Finished goods	132.0	70.6
Deferred costs	505.7	400.9
Total Inventories	$ 1,640.9	$ 1,415.5

Debt - Narrative (Details) - USD ($)	6 Months Ended
Debt - Narrative (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Debt	$ 1,500,000,000.0	$ 0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 750,000,000.0
Debt term	5 years
Bridge Facility \| Bridge Facility
Line of Credit Facility [Line Items]
Debt	$ 1,500,000,000
Bridge Facility \| Common Stock Held By Sanofi \| Bridge Facility
Line of Credit Facility [Line Items]
Debt, principal amount	$ 1,500,000,000
Interest rate	2.75%

Income Taxes (Details)	3 Months Ended		6 Months Ended
Income Taxes (Details)	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Effective income tax rate	2.40%	14.10%	4.10%	15.10%

Stockholders' Equity - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended			6 Months Ended
Stockholders' Equity - Narrative (Details) - USD ($)	May 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Jun. 30, 2020	Nov. 30, 2019
Class of Stock [Line Items]
Treasury stock, shares acquired (in shares)	9,806,805
Cost of treasury stock received	$ 5,000,000,000	$ 5,071,800,000	$ 336,000,000.0	$ 54,000,000.0
Sanofi
Class of Stock [Line Items]
Number of shares sold (in shares)	13,014,646
Common Stock, shares outstanding (in shares)	400,000
Share Repurchase Program
Class of Stock [Line Items]
Share repurchase program, authorized amount						$ 1,000,000,000.0
Treasury stock, shares acquired (in shares)		0			719,167
Remaining authorized repurchase amount		$ 473,100,000			$ 473,100,000
Cost of treasury stock received					$ 272,800,000

Stockholders' Equity - Schedule of Repurchased Shares (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended			6 Months Ended
	May 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Jun. 30, 2020
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased (in shares)	9,806,805
Total cost of shares received	$ 5,000.0	$ 5,071.8	$ 336.0	$ 54.0
Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased (in shares)		0			719,167
Total cost of shares received					$ 272.8

Stockholders' Equity - Sanofi Funding (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended				6 Months Ended
	May 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares acquired (in shares)	9,806,805
Total cost of shares received	$ 5,000.0	$ 5,071.8	$ 336.0		$ 54.0
Libtayo development
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares acquired (in shares)		34,050		0		77,677	106,972
Total cost of shares received		$ 20.3		$ 0.0		$ 41.7	$ 44.0
Dupilumab/REGN3500 Eligible Investments
Equity, Class of Treasury Stock [Line Items]
Treasury stock, shares acquired (in shares)		86,184		0		171,471	24,143
Total cost of shares received		$ 51.5		$ 0.0		$ 93.3	$ 10.0

Statement of Cash Flows - Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents	$ 1,992.2	$ 1,617.8	$ 1,045.5
Restricted cash included in Other noncurrent assets	12.5		12.5
Total cash, cash equivalents, and restricted cash shown in the Condensed Consolidated Statement of Cash Flows	$ 2,004.7	$ 1,630.3	$ 1,058.0	$ 1,480.2

Statement of Cash Flows - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Accrued capital expenditures	$ 87.4	$ 133.7	$ 74.7	$ 54.5

Legal Matters (Details) $ in Millions	Jul. 16, 2020 claim	Jul. 31, 2017 claim	Sep. 26, 2016 EUR (€)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Feb. 25, 2019 claim	Feb. 14, 2019 claim
Loss Contingencies [Line Items]
Loss contingency accrual \| $				$ 132.2	$ 100.0
Amgen v.s. Regeneron \| Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, damages sought, per unit produced \| €			€ 10,000
Loss contingency, damages sought \| €			€ 10,000,000.0
'165 Patent \| Amgen v.s. Regeneron \| Pending Litigation
Loss Contingencies [Line Items]
Pending claims						2
Invalid claims						2
'741 Patent \| Amgen v.s. Regeneron \| Pending Litigation
Loss Contingencies [Line Items]
Pending claims						1
'487 Patent
Loss Contingencies [Line Items]
Number of IPR filed		2
Number of claims invalidated							17
'631 Patent \| Subsequent Event
Loss Contingencies [Line Items]
Number of IPR filed	2

Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	$ 2,934.5	$ 4,234.5
Measured on a recurring basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	789.7	618.8
Measured on a recurring basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	2,949.9	4,234.5
Unrestricted \| Measured on a recurring basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	37.8	61.6
Unrestricted \| Measured on a recurring basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	0.0	0.0
Restricted \| Measured on a recurring basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	751.9	557.2
Restricted \| Measured on a recurring basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	15.4	0.0
Estimate of Fair Value Measurement \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total marketable securities	3,739.6	4,853.3
Estimate of Fair Value Measurement \| Unrestricted \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	37.8	61.6
Estimate of Fair Value Measurement \| Restricted \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	767.3	557.2
Corporate bonds \| Measured on a recurring basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	0.0	0.0
Corporate bonds \| Measured on a recurring basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	2,434.4	3,988.1
Corporate bonds \| Unrestricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	2,434.4	3,988.1
Corporate bonds \| Estimate of Fair Value Measurement \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	2,434.4	3,988.1
U.S. government and government agency obligations \| Measured on a recurring basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	0.0	0.0
U.S. government and government agency obligations \| Measured on a recurring basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	82.7	54.4
U.S. government and government agency obligations \| Unrestricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	82.7	54.4
U.S. government and government agency obligations \| Estimate of Fair Value Measurement \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	82.7	54.4
Sovereign bonds \| Measured on a recurring basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	0.0	0.0
Sovereign bonds \| Measured on a recurring basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	28.2	27.3
Sovereign bonds \| Unrestricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	28.2	27.3
Sovereign bonds \| Estimate of Fair Value Measurement \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	28.2	27.3
Commercial paper \| Measured on a recurring basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	0.0	0.0
Commercial paper \| Measured on a recurring basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	283.7	92.3
Commercial paper \| Unrestricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	283.7	92.3
Commercial paper \| Estimate of Fair Value Measurement \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	283.7	92.3
Certificates of deposit \| Measured on a recurring basis \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	0.0	0.0
Certificates of deposit \| Measured on a recurring basis \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	105.5	72.4
Certificates of deposit \| Unrestricted
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	105.5	72.4
Certificates of deposit \| Estimate of Fair Value Measurement \| Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale debt securities:	$ 105.5	$ 72.4