Interim Financial Statements - Schedule of Statements of Operations Data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 1,663,496	$ 1,500,673	$ 4,783,003	$ 4,289,780
Income from operations	626,923	559,926	1,816,342	1,540,780
Income before income taxes	635,861	565,605	1,877,333	1,523,744
Income tax expense	(41,206)	(177,288)	(253,286)	(498,752)
Net income	594,655	388,317	1,624,047	1,024,992
Collaboration and contract manufacturing
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold	79,552	57,844	180,918	141,547
Balance Without Adoption of ASC 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	1,700,242		4,755,229
Income from operations	681,187		1,806,086
Income before income taxes	690,125		1,867,077
Income tax expense	(43,869)		(248,656)
Net income	646,256		1,618,421
Balance Without Adoption of ASC 606 | Collaboration and contract manufacturing
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold	62,034		163,400
Accounting Standards Update 2014-09 | Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	36,746		(27,774)
Income from operations	54,264		(10,256)
Income before income taxes	54,264		(10,256)
Income tax expense	(2,663)		4,630
Net income	51,601		(5,626)
Accounting Standards Update 2014-09 | Adjustments | Collaboration and contract manufacturing
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of goods sold	(17,518)		(17,518)
Sanofi | Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	256,265	245,175	683,508	677,670
Sanofi | Balance Without Adoption of ASC 606 | Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	268,437		678,349
Sanofi | Accounting Standards Update 2014-09 | Adjustments | Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	12,172		(5,159)
Other | Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	117,370	$ 61,506	314,552	$ 231,446
Other | Balance Without Adoption of ASC 606 | Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	141,944		291,937
Other | Accounting Standards Update 2014-09 | Adjustments | Product and service, other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 24,574		$ (22,615)