Collaborative Arrangements - Collaborative Arrangements Narrative (Details) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($)
Collaborative Arrangements [Abstract]
Collaboration Agreement, Initial Consideration Transferred	$ 165
Other Research and Development Expense	$ 126

Amount of other research and development expense.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

Name:	us-gaap_OtherResearchAndDevelopmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration