Return of or reimbursements received in relation to direct costs and expenses previously paid or incurred.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_RecoveryOfDirectCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Collaborations (Details) - Collaborative arrangement with Novartis Pharma AG [Member] - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Apr. 30, 2017
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential Future Milestone Payments					$ 400,000,000
Research and development expense [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Recovery of Direct Costs	$ 31,000,000	$ 11,000,000	$ 57,000,000	$ 20,000,000