Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest (SRX Cardio)
Balance at beginning of year (in shares) at Dec. 31, 2016		56,544
Balance at beginning of year at Dec. 31, 2016	$ 192,689	$ 57	$ 1,108,832	$ (918,345)	$ (12)	$ 2,157
Cumulative effect of a change in accounting principal			84	(84)
Issuance of common stock pursuant to equity award plans (in shares)		1,450
Issuance of common stock pursuant to equity award plans	19,643	$ 2	19,641
Issuance of common stock in connection with public offering, net (in shares)		7,303
Issuance of common stock pursuant to public offering, net	379,894	$ 7	379,887
Stock-based compensation expense	43,284		43,284
Other comprehensive income	(397)				(397)
Net (loss) gain	(285,620)			(286,090)		470
Balance at end of the year (in shares) at Dec. 31, 2017		65,297
Balance at end of the year at Dec. 31, 2017	349,493	$ 66	1,551,728	(1,204,519)	(409)	2,627
Adjustment to accumulated deficit due to adoption of ASC 606	29,038			29,038
Issuance of common stock pursuant to equity award plans (in shares)		1,321
Issuance of common stock pursuant to equity award plans	15,389	$ 2	15,387
Stock-based compensation expense	47,205		47,205
Other comprehensive income	126				126
Net (loss) gain	(350,544)			(350,223)		(321)
Change in noncontrolling interest	(140)					(140)
Balance at end of the year (in shares) at Dec. 31, 2018		66,618
Balance at end of the year at Dec. 31, 2018	90,567	$ 68	1,614,320	(1,525,704)	(283)	2,166
Issuance of common stock pursuant to equity award plans (in shares)		2,066
Issuance of common stock pursuant to equity award plans	39,921	$ 3	39,918
Issuance of common stock in connection with public offering, net (in shares)		9,241
Issuance of common stock pursuant to public offering, net	243,940	$ 9	243,931
Stock-based compensation expense	47,908		47,908
Other comprehensive income	318				318
Net (loss) gain	(292,876)			(290,663)		(2,213)
Change in noncontrolling interest	47					47
Balance at end of the year (in shares) at Dec. 31, 2019		77,925
Balance at end of the year at Dec. 31, 2019	$ 129,825	$ 80	$ 1,946,077	$ (1,816,367)	$ 35	$ 0