License, Collaboration and Other Significant Agreements - Deferred Revenues Balance (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Deferred Revenue:
Short-Term	$ 49,584	$ 56,980
Long-Term	56,887	$ 55,709
Total	106,471
Otsuka Pharmaceutical Company. Ltd. \| U.S.
Deferred Revenue:
Short-Term	29,115
Long-Term	33,303
Total	62,418
Otsuka Pharmaceutical Company. Ltd. \| International
Deferred Revenue:
Short-Term	20,469
Long-Term	18,905
Total	39,374
Vifor Pharma
Deferred Revenue:
Long-Term	4,679
Total	$ 4,679

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130532-203044

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Name:	us-gaap_ContractWithCustomerLiabilityNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant