Collaboration Agreements Adicet Bio (Details) - Adicet Bio [Member] - Collaborative Arrangement [Member] $ in Millions	9 Months Ended
Sep. 30, 2016 USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Other Research and Development Expense	$ 25.0
Research and Development Arrangement, Contract to Perform for Others, Description and Terms	5

Describes the terms of significant agreements under research and development arrangements accounted for as a contract to perform research and development for others (including royalty arrangements, purchase provisions, license agreements, and commitments to provide additional funding), aggregated by similar arrangements or individually if necessary to understand the effects on the financial statements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6420387&loc=d3e23199-108380

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6420387&loc=d3e23221-108380

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