Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2020	$ 244,344	$ 1	$ 412,589	$ (168,192)	$ (54)
Balance (in shares) at Dec. 31, 2020		73,215,940
Employee stock-based compensation	1,577		1,577
Shares withheld related to employee tax withholding	(473)		(473)
Shares withheld related to employee tax withholding (in shares)		(81,016)
Issuance of common stock under employee stock plans	156		156
Issuance of common stock under employee stock plans (in shares)		236,932
Issuance of common stock from warrant exercises	5,679		5,679
Issuance of common stock from warrant exercises (in shares)		3,806,225
Unrealized loss on investments	(50)				(50)
Net loss	(14,010)			(14,010)
Balance at Mar. 31, 2021	237,223	$ 1	419,528	(182,202)	(104)
Balance (in shares) at Mar. 31, 2021		77,178,081
Balance at Dec. 31, 2021	201,884	$ 1	425,614	(223,182)	(549)
Balance (in shares) at Dec. 31, 2021		78,248,401
Employee stock-based compensation	2,357		2,357
Shares withheld related to employee tax withholding	(499)		(499)
Shares withheld related to employee tax withholding (in shares)		(105,475)
Issuance of common stock under employee stock plans (in shares)		222,503
Issuance of common stock from warrant exercises	614		614
Issuance of common stock from warrant exercises (in shares)		472,500
Repurchase of common stock	(5,121)					$ (5,121)
Repurchase of common stock (in shares)		(1,464,217)
Unrealized loss on investments	(893)				(893)
Unrealized currency translation gains	31				31
Net loss	(16,103)			(16,103)
Balance at Mar. 31, 2022	$ 182,270	$ 1	$ 428,086	$ (239,285)	$ (1,411)	$ (5,121)
Balance (in shares) at Mar. 31, 2022		77,373,712