Collaborative Arrangements and Acquisitions - Cystic Fibrosis Foundation Therapeutics Incorporated (Details) - Cystic Fibrosis Foundation Therapeutics Incorporated - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2019	Dec. 31, 2016
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Additional milestone payments	$ 0
Collaborative funding		$ 75,000,000.0
Additional collaborative funding		$ 6,000,000.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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