Business Combinations (Details) - USD ($) $ in Thousands			1 Months Ended	3 Months Ended	9 Months Ended
	Jun. 02, 2016	Jun. 02, 2016	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2016
Preliminary allocation of purchase consideration
Cash payments					$ 100,000
Identifiable assets acquired
Goodwill				$ 649	649
Business combination other disclosures
Changes in fair value				8,667	$ 8,667
Licensing agreement | AstraZeneca
Business Combinations
Royalty percentage per agreement					single digits
Milestone payment to be paid by company upon milestone achievement					$ 165,000
Product related collaborative arrangements | AstraZeneca | Developed technology - ZURAMPIC
Business Combinations
Total milestone payments to be paid by company		$ 100,000
Period for reimbursement amount of development activities (in years)		10 years
Lesinurad transaction | AstraZeneca
Business Combinations
Acquisition related issuance costs			$ 1,600
Preliminary allocation of purchase consideration
Cash payments		$ 100,000
Contingent consideration	$ 87,649
Total consideration		187,649
Identifiable assets acquired
Goodwill	649	649
Total identifiable assets acquired	187,649	187,649
Business combination other disclosures
Impairment of goodwill					0
Lesinurad transaction | AstraZeneca | IPR&D - FDC Product
Identifiable assets acquired
In-process research and development	19,100	$ 19,100
Business combination other disclosures
Discount rate applied to determine fair value (as a percent)		16.00%
Remaining cost of development for intangible asset				13,900	13,900
Impairment of indefinite-lived intangible					0
Lesinurad transaction | AstraZeneca | Developed technology - ZURAMPIC
Identifiable assets acquired
Developed technology	$ 167,900	$ 167,900
Business combination other disclosures
Discount rate applied to determine fair value (as a percent)		13.50%
Estimated useful life		13 years
Accumulated amortization of intangible assets				4,300	4,300
Impairment of finite-lived intangible					0
Estimated future amortization expense
2016				3,207	3,207
2017				12,833	12,833
2018				12,833	12,833
2019				12,833	12,833
2020 and thereafter				121,916	121,916
Total				$ 163,622	$ 163,622
Lesinurad transaction | Commercial Supply Agreement (CSA) | AstraZeneca
Business Combinations
Time period for manufacturing technology transfer per agreement		6 months