Summary of Significant Accounting Policies - Subsequent Event (Details) - USD ($) $ in Thousands		3 Months Ended
May 01, 2018	Mar. 31, 2018
Subsequent Event [Line Items]
Revenue recognized		$ 11,540
Takeda
Subsequent Event [Line Items]
Revenue recognized		$ 10,900
Subsequent event \| Takeda
Subsequent Event [Line Items]
Revenue recognized	$ 5,000

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130549-203045

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 270
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84173487&loc=SL51747714-108306

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