Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net loss	$ (84,510)	$ (41,764)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	756	504
Net amortization/accretion on investment securities	(491)	161
Non-cash interest expense	2,581	1,639
Stock-based compensation expense	10,980	9,034
Remeasurement gain on embedded derivatives liabilities	(1,634)
Changes in operating assets and liabilities:
Inventories	(2,149)
Trade and other receivables, net	4,763
Unbilled - collaboration and license revenue	2,034
Prepaid research and development	(2,715)	1,401
Prepaid expenses and other current assets	(8,529)	(632)
Prepaid and other long-term assets	4,797	1,046
Accounts payable	11,469	(5,123)
Accrued compensation and employee benefits	(6,413)	(1,407)
Accrued research and development	(22,868)	(12,649)
Accrued and other liabilities	2,089	1,587
Deferred revenue	1,650	(5,128)
Other long-term liabilities	(230)	(205)
Net cash used in operating activities	(88,420)	(51,536)
Investing activities
Purchases of property and equipment	(512)	(113)
Purchases of investments	(78,048)	(147,781)
Proceeds from maturities of investments	148,141	95,304
Net cash provided by (used in) investing activities	69,581	(52,590)
Financing activities
Proceeds from debt issuance, net		48,000
Debt issuance costs paid		(536)
Proceeds from issuance of common stock pursuant to equity award plans	5,679	3,847
Dividends to Noncontrolling interest (SRX Cardio)'s shareholders	(120)
Net cash provided by financing activities	5,559	51,311
Net decrease in cash, cash equivalents and restricted cash	(13,280)	(52,815)
Cash, cash equivalents and restricted cash at beginning of period	181,741	188,658
Cash, cash equivalents and restricted cash at end of period	$ 168,461	$ 135,843