Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance, beginning (in shares) at Dec. 31, 2019		37,996,849
Balance, beginning at Dec. 31, 2019	$ 141,687		$ 441,216	$ (299,529)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued upon exercises of stock options (in shares)	376,311	376,311
Shares issued upon exercises of stock options	$ 3,392		3,392
Shares issued upon vesting of restricted stock units (in shares)		13,000
Stock-based compensation	683		683
Net loss	(8,642)			(8,642)
Balance, ending (in shares) at Mar. 31, 2020		38,386,160
Balance, ending at Mar. 31, 2020	137,120		445,291	(308,171)
Balance, beginning (in shares) at Dec. 31, 2020		42,196,296
Balance, beginning at Dec. 31, 2020	$ 191,216		524,022	(332,806)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued upon exercises of stock options (in shares)	91,737	91,737
Shares issued upon exercises of stock options	$ 282		282
Shares issued upon vesting of restricted stock units (in shares)		38,000
Stock-based compensation	2,420		2,420
Net loss	(14,950)			(14,950)
Balance, ending (in shares) at Mar. 31, 2021		42,326,033
Balance, ending at Mar. 31, 2021	$ 178,968		$ 526,724	$ (347,756)