Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Collaborative arrangements revenue	$ 64,612	$ 54,350	$ 116,489	$ 120,392
Product revenue, net	465		754
Total revenues	65,077	54,350	117,243	120,392
Cost and expenses:
Cost of revenues, excluding amortization of acquired intangible asset	3,502		4,033
Write-down of lesinurad commercial supply to net realizable value and loss on non-cancellable purchase commitments	96		96
Research and development	37,344	31,682	71,046	63,524
Selling, general and administrative	57,792	36,918	113,396	73,086
Amortization of acquired intangible asset	421	1,065	841	1,065
Loss on fair value remeasurement of contingent consideration	6,933		8,547
Total cost and expenses	106,088	69,665	197,959	137,675
Loss from operations	(41,011)	(15,315)	(80,716)	(17,283)
Other (expense) income:
Interest expense	(9,046)	(9,827)	(18,029)	(19,734)
Interest and investment income	496	295	891	516
Gain on derivatives	5,337	3,145	3,138	1,502
Loss on extinguishment of debt			(2,009)
Other expense, net	(3,213)	(6,387)	(16,009)	(17,716)
Net loss	$ (44,224)	$ (21,702)	$ (96,725)	$ (34,999)
Net loss per share—basic and diluted	$ (0.30)	$ (0.15)	$ (0.65)	$ (0.24)
Weighted average number of common shares used in net loss per share—basic and diluted:	148,778	144,642	148,285	144,118