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-Section 50
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-Publisher FASB
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-Section 45
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Collaboration and License Agreements - Schedule of Significant Changes in Deferred Revenue Balances, IO Collaboration (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Increase as a result of cumulative-effect adjustment arising from the adoption of ASC 606	$ (194.5)	$ (113.1)	$ 244.3
Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Revenue recognized that was included in deferred revenue at the beginning of the period	(108.7)
Accounting Standards Update 2014-09 \| Sanofi Collaboration Agreement, Immuno-oncology
Disaggregation of Revenue [Line Items]
Increase as a result of cumulative-effect adjustment arising from the adoption of ASC 606	$ 93.6