Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net loss	$ (43,144)	$ (52,501)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,790	2,910
Amortization of acquired intangible assets	3,476	420
Gain on disposal of property and equipment	(34)
Share-based compensation expense	9,043	7,279
Change in fair value of note hedge warrants	3,941	20,187
Change in fair value of convertible note hedges	(5,257)	(17,988)
Write-down of excess non-cancellable ZURAMPIC sample purchase commitments		1,353
Gain on facility subleases		(1,579)
Accretion of discount/premium on investment securities	(118)	105
Non-cash interest expense	4,239	3,877
Non-cash change in fair value of contingent consideration	512	1,614
Loss on extinguishment of debt		2,009
Changes in assets and liabilities:
Accounts receivable and related party accounts receivable	11,506	13,707
Prepaid expenses and other current assets	(1,647)	372
Inventory	(768)	71
Other assets	62	201
Accounts payable, related party accounts payable and accrued expenses	(12,300)	(5,238)
Accrued research and development costs	(2,640)	(1,831)
Deferred revenue		741
Deferred rent	453	(3,555)
Net cash used in operating activities	(30,886)	(27,846)
Cash flows from investing activities:
Purchases of available-for-sale securities	(2,491)	(44,777)
Sales and maturities of available-for-sale securities	48,620	133,830
Purchases of property and equipment	(1,509)	(1,037)
Proceeds from sale of property and equipment	33	43
Net cash provided by investing activities	44,653	88,059
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		(209)
Proceeds from exercise of stock options and employee stock purchase plan	6,203	8,171
Payments on capital leases	(827)	(796)
Principal payments on PhaRMA notes		(134,258)
Payments on contingent purchase price consideration	(91)	(56)
Net cash provided by financing activities	5,285	19,102
Net increase in cash, cash equivalents and restricted cash	19,052	79,315
Cash, cash equivalents and restricted cash, beginning of period	132,792	62,251
Cash, cash equivalents and restricted cash, end of period	151,844	141,566
Reconciliation of cash, cash equivalents, and restricted cash to the condensed consolidated balance sheets
Cash and cash equivalents	144,788	133,319
Restricted cash	7,056	8,247
Total Cash, cash equivalents, and restricted cash	$ 132,792	$ 62,251