Product Sales - Schedule of Net Product Sales (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 2,048.4	$ 1,663.5	$ 5,693.9	$ 4,783.0
Product
Disaggregation of Revenue [Line Items]
Revenues	1,238.3	1,025.5	3,548.0	3,009.8
UNITED STATES \| EYLEA
Disaggregation of Revenue [Line Items]
Revenues	1,187.7	1,021.8	3,422.1	2,997.8
UNITED STATES \| Libtayo
Disaggregation of Revenue [Line Items]
Revenues	47.6	0.0	115.2	0.0
UNITED STATES \| ARCALYST
Disaggregation of Revenue [Line Items]
Revenues	3.0	3.7	10.7	12.0
UNITED STATES \| Product
Disaggregation of Revenue [Line Items]
Revenues	$ 1,238.3	$ 1,025.5	$ 3,548.0	$ 3,009.8

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration