STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Beginning balance (in shares) at Dec. 31, 2019			24,107,350
Beginning balance at Dec. 31, 2019	$ 139,835	$ 12	$ 24	$ 319,865	$ 102	$ (180,156)	$ 12
Stockholders' Equity [Roll Forward]
Stock options exercised (in shares)			254,142
Stock options exercised	787		$ 0	787
Issuance of common stock (in shares)			897
Issuance of common stock	72			72
Stock-based compensation expense	2,749			2,749
Other comprehensive income (loss)	193				193
Net loss	(16,245)					(16,245)
Ending balance (in shares) at Mar. 31, 2020			24,362,389
Ending balance at Mar. 31, 2020	$ 127,403		$ 24	323,473	295	(196,389)
Beginning balance (in shares) at Dec. 31, 2020	27,069,276		27,069,276
Beginning balance at Dec. 31, 2020	$ 229,747		$ 27	467,038	29	(237,347)
Stockholders' Equity [Roll Forward]
Stock options exercised (in shares)	133,421		133,421
Stock options exercised	$ 3,550			3,550
Issuance of common stock (in shares)			376
Issuance of common stock	73			73
Stock-based compensation expense	5,997			5,997
Other comprehensive income (loss)	(20)				(20)
Net loss	$ (16,216)					(16,216)
Ending balance (in shares) at Mar. 31, 2021	27,203,073		27,203,073
Ending balance at Mar. 31, 2021	$ 223,131		$ 27	$ 476,658	$ 9	$ (253,563)