Condensed Unaudited Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional paid-in capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period (in shares) at Dec. 31, 2019		0	49,627
Balance at beginning of period at Dec. 31, 2019	$ 117,203	$ 0	$ 50	$ 597,679	$ (480,526)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plan (in shares)			105
Issuance of common stock under employee stock compensation plans	179			179
Share-based compensation	2,324			2,324
Net loss	(15,076)				(15,076)
Balance at end of period (in shares) at Mar. 31, 2020		0	49,732
Balance at end of period at Mar. 31, 2020	104,630	$ 0	$ 50	600,182	(495,602)	$ 0
Balance at beginning of period (in shares) at Dec. 31, 2020		0	90,121
Balance at beginning of period at Dec. 31, 2020	191,563	$ 0	$ 90	756,543	(565,073)	3
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plan (in shares)			49
Issuance of common stock under employee stock compensation plans	129			129
Share-based compensation	2,292			2,292
Net loss	(26,795)				(26,795)
Unrealized loss on available for sale securities, net of tax	(1)					(1)
Balance at end of period (in shares) at Mar. 31, 2021		0	90,170
Balance at end of period at Mar. 31, 2021	$ 167,188	$ 0	$ 90	$ 758,964	$ (591,868)	$ 2