Collaboration and License Agreements - Schedule of Significant Changes in Deferred Revenue Balances, Antibody Collaboration (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
(Decrease) increase in deferred revenue	$ (194.5)	$ (113.1)	$ 244.3
Sanofi Collaboration Agreement, Antibody
Disaggregation of Revenue [Line Items]
(Decrease) increase in deferred revenue	251.6
Revenue recognized that was included in deferred revenue at the beginning of the period	$ (133.2)

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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