CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative-effect Adjustment from Adoption of ASU 2020-06	Common Stock	Additional Paid-In-Capital	Additional Paid-In-Capital Cumulative-effect Adjustment from Adoption of ASU 2020-06	Accumulated Deficit	Accumulated Deficit Cumulative-effect Adjustment from Adoption of ASU 2020-06	Accumulated Other Comprehensive Income
Beginning balance at Dec. 31, 2019	$ 125,239		$ 22	$ 387,926		$ (262,743)		$ 34
Beginning balance, shares at Dec. 31, 2019			22,217
Issuance of common stock	2,014		$ 1	2,013
Issuance of common stock, shares			460
Stock-based compensation	5,221			5,221
Net loss	(4,326)					(4,326)
Other comprehensive income	71							71
Ending balance at Mar. 31, 2020	128,219		$ 23	395,160		(267,069)		105
Ending balance, shares at Mar. 31, 2020			22,677
Beginning balance at Dec. 31, 2020	$ 109,119	$ (29,301)	$ 23	423,759	$ (32,743)	(314,666)	$ 3,442	3
Beginning balance, shares at Dec. 31, 2020			23,350
Accounting Standards Update [Extensible List]	ASU 2020-06
Issuance of common stock	$ 8,524		$ 1	8,523
Issuance of common stock, shares			702
Stock-based compensation	7,449			7,449
Net loss	(9,416)					(9,416)
Ending balance at Mar. 31, 2021	$ 86,375		$ 24	$ 406,988		$ (320,640)		$ 3
Ending balance, shares at Mar. 31, 2021			24,052