Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net loss	$ (350,544)	$ (285,620)	$ (268,113)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	3,102	2,410	1,924
Net (accretion) amortization on investment securities	(1,864)	(235)	1,113
Non-cash interest expense	18,740	11,603	61
Stock-based compensation expense, net of capitalized labor	46,159	43,284	30,362
Stock-based compensation expense for Lonza liability-classified award	9,201
Charge associated with our Gen 1 manufacturing process transition	10,311
Remeasurement (gain) loss on embedded derivatives liabilities	(6,357)	4,562
Provision for excess and obsolete inventories	2,246
Loss on assets disposal	15	52
Changes in operating assets and liabilities:
Inventories	(12,612)	(1,099)
Trade and other receivables, net	607	(3,750)	1,000
Unbilled - collaboration and license revenue	(3,186)
Prepaid expenses and other current assets	(7,496)	235	10,055
Prepaid and other long-term assets	(10,968)	(4,395)	6,779
Accounts payable	1,881	(5,242)	4,308
Accrued compensation and employee benefits	(732)	6,720	(653)
Accrued research and development	(25,142)	21,155	(377)
Accrued and other liabilities	4,246	1,856	(892)
Deferred revenue	(1,288)	(15,796)	18,747
Notes payable, long term debt and long term obligation to collaborator	(1,412)
Other long-term liabilities	(965)	(865)	(769)
Net cash used in operating activities	(326,058)	(225,125)	(196,455)
Investing activities
Purchases of property and equipment	(2,559)	(1,236)	(1,864)
Purchases of intangible assets		(5,000)
Purchases of investments	(259,083)	(575,624)	(252,323)
Proceeds from maturities of investments	435,723	353,088	394,730
Net cash provided by (used in) investing activities	174,081	(228,772)	140,543
Financing activities
Proceeds from debt issuance, net	95,000	47,444
Proceeds from issuance of common stock from public offering, net		379,894
Proceeds from issuance of common stock based on equity award plans, net	15,389	19,642	1,441
Dividends to Noncontrolling interest (SRX Cardio)'s shareholders	(140)		(1,700)
Proceeds from long-term notes payable			50,000
Proceeds from long-term obligation to Collaborator			8,000
Net cash provided by financing activities	110,249	446,980	57,741
Net (decrease) increase in cash, cash equivalents and restricted cash	(41,728)	(6,917)	1,829
Cash, cash equivalents and restricted cash at beginning of period	181,741	188,658	186,829
Cash, cash equivalents and restricted cash at end of period	$ 140,013	$ 181,741	188,658
Noncash investing and financing activities:
Net change in accrued offering cost			$ (238)