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Name:	us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Commitments and Contingencies - Strategic Collaborations (Details) - PCV Agreement - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2016
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Budgeted amount			$ 250.0
PCV products
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Budgeted amount	$ 243.0	$ 243.0