Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Underwritten Offering	Private Placement	Junior Series A Preferred Stock	Common Stock	Common Stock Underwritten Offering	Common Stock Private Placement	Additional paid-in capital	Additional paid-in capital Underwritten Offering	Additional paid-in capital Private Placement	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period (in shares) at Dec. 31, 2017				0	36,110
Balance at beginning of period at Dec. 31, 2017	$ 38,041			$ 0	$ 36			$ 522,759			$ (484,754)	$ 0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to acquisition (in shares)					5,175
Issuance of common stock related to acquisition	11,694				$ 5			11,689
Issuance of common stock under employee stock compensation plans and warrants (in shares)					112
Issuance of common stock under employee stock compensation plans and warrants	65				$ 0			65
Share-based compensation	11,072							11,072
Net income	63,087										63,087
Unrealized gain on available for sale securities, net of tax	0
Balance at end of period (in shares) at Dec. 31, 2018				0	41,397
Ending balance at Dec. 31, 2018	123,959			$ 0	$ 41			545,585			(421,667)	0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock and pre-funded warrants, net (in shares)					7,750
Issuance of common stock and pre-funded warrants, net	42,565				$ 8			42,557
Issuance of common stock related to acquisition (in shares)					75
Issuance of common stock related to acquisition	85							85
Issuance of common stock under employee stock compensation plans (in shares)					405
Issuance of common stock under employee stock compensation plans	273				$ 1			272
Share-based compensation	9,180							9,180
Net income	(58,859)										(58,859)
Unrealized gain on available for sale securities, net of tax	0
Balance at end of period (in shares) at Dec. 31, 2019				0	49,627
Ending balance at Dec. 31, 2019	117,203			$ 0	$ 50			597,679			(480,526)	0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock and pre-funded warrants, net (in shares)					2,500	28,504	8,649
Issuance of common stock and pre-funded warrants, net	0	$ 116,883	$ 33,237		$ 2	$ 28	$ 9	(2)	$ 116,855	$ 33,228
Issuance of common stock under employee stock compensation plans and warrants (in shares)					841
Issuance of common stock under employee stock compensation plans and warrants	461				$ 1			460
Share-based compensation	8,323							8,323
Net income	(84,547)										(84,547)
Unrealized gain on available for sale securities, net of tax	3											3
Balance at end of period (in shares) at Dec. 31, 2020				0	90,121
Ending balance at Dec. 31, 2020	$ 191,563			$ 0	$ 90			$ 756,543			$ (565,073)	$ 3