Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (96,725)	$ (34,999)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,838	5,320
Amortization of acquired intangible asset	841	1,065
Loss on disposal of property and equipment	135
Share-based compensation expense	16,419	14,903
Change in fair value of note hedge warrants	36,221	11,510
Change in fair value of convertible note hedges	(39,359)	(13,012)
Write-down of excess non-cancelable ZURAMPIC finished goods inventory and sample purchase commitments	1,353
Write-down of lesinurad commercial supply to net realizable value and loss on non-cancellable purchase commitments	96
(Gain) loss on facility subleases	(1,579)	3,480
Accretion of discount/premium on investment securities	111	457
Non-cash interest expense	7,849	7,221
Non-cash change in fair value of contingent consideration	8,547
Loss on extinguishment of debt	2,009
Changes in assets and liabilities:
Accounts receivable and related party accounts receivable	4,497	1,371
Restricted cash	1,190	500
Prepaid expenses and other current assets	703	(1,265)
Inventory	1,081
Other assets	246	810
Accounts payable, related party accounts payable and accrued expenses	(5,345)	(2,314)
Accrued research and development costs	517	2,408
Deferred revenue	225	(470)
Deferred rent	(2,977)	(3,087)
Net cash (used in) provided by operating activities	(59,107)	(6,102)
Cash flows from investing activities:
Purchases of available-for-sale securities	(90,706)	(52,629)
Sales and maturities of available-for-sale securities	251,027	182,363
Purchases of property and equipment	(1,746)	(1,623)
Payment for acquisition of lesinurad license		(100,000)
Proceeds from sale of property and equipment	79
Net cash used in by investing activities	158,654	28,111
Cash flows from financing activities:
Proceeds from issuance of 2026 Notes, net of discount to lender	146,250
Costs associated with issuance of 2026 Notes	(235)
Proceeds from exercise of stock options and employee stock purchase plan	18,473	6,163
Payments on capital leases	(1,593)	(828)
Principal payments on PhaRMA notes	(134,258)	(11,299)
Payments on contingent purchase price consideration	(56)
Net cash provided by (used in) financing activities	28,581	(5,964)
Net increase in cash and cash equivalents	128,128	16,045
Cash and cash equivalents, beginning of period	54,004	261,287
Cash and cash equivalents, end of period	$ 182,132	277,332
Non-cash investing activities
Contingent consideration		$ 87,649