Condensed Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance, Value at Dec. 31, 2019	$ 47	$ 587,223	$ (400,727)	$ 170	$ 186,713
Balance, Shares at Dec. 31, 2019	46,720,225
Stock-based compensation expense		2,846			2,846
Shares issued upon exercise of stock options, value		75			75
Shares issued upon exercise of stock options, shares	7,500
Net Loss			(28,922)		(28,922)
Other comprehensive loss				(238)	(238)
Balance, Value at Mar. 31, 2020	$ 47	590,144	(429,649)	(68)	160,474
Balance, Shares at Mar. 31, 2020	46,727,725
Balance, Value at Dec. 31, 2019	$ 47	587,223	(400,727)	170	186,713
Balance, Shares at Dec. 31, 2019	46,720,225
Net Loss					(53,990)
Other comprehensive loss				465
Balance, Value at Jun. 30, 2020	$ 47	594,963	(454,717)	635	140,928
Balance, Shares at Jun. 30, 2020	46,864,405
Balance, Value at Mar. 31, 2020	$ 47	590,144	(429,649)	(68)	160,474
Balance, Shares at Mar. 31, 2020	46,727,725
Stock-based compensation expense		2,993			2,993
Shares issued upon exercise of stock options, value		201			201
Shares issued upon exercise of stock options, shares	16,846
Shares issued upon vesting of restricted stock units, value		1,625			1,625
Shares issued upon vesting of restricted stock units, shares	119,834
Net Loss			(25,068)		(25,068)
Other comprehensive loss				703	703
Balance, Value at Jun. 30, 2020	$ 47	594,963	(454,717)	635	140,928
Balance, Shares at Jun. 30, 2020	46,864,405
Balance, Value at Dec. 31, 2020	$ 50	641,195	(392,317)	73	249,001
Balance, Shares at Dec. 31, 2020	49,872,213
Stock-based compensation expense		2,744			2,744
Shares issued upon exercise of stock options, value		688			688
Shares issued upon exercise of stock options, shares	45,035
Shares issued upon vesting of restricted stock units, value		1,388			1,388
Shares issued upon vesting of restricted stock units, shares	109,419
Net Loss			(23,301)		(23,301)
Other comprehensive loss				(61)	(61)
Balance, Value at Mar. 31, 2021	$ 50	646,015	(415,618)	12	230,459
Balance, Shares at Mar. 31, 2021	50,026,667
Balance, Value at Dec. 31, 2020	$ 50	641,195	(392,317)	73	249,001
Balance, Shares at Dec. 31, 2020	49,872,213
Net Loss					(54,046)
Other comprehensive loss				(78)
Balance, Value at Jun. 30, 2021	$ 50	649,784	(446,363)	(5)	203,466
Balance, Shares at Jun. 30, 2021	50,088,161
Balance, Value at Mar. 31, 2021	$ 50	646,015	(415,618)	12	230,459
Balance, Shares at Mar. 31, 2021	50,026,667
Stock-based compensation expense		3,376			3,376
Shares issued upon exercise of stock options, value		293			293
Shares issued upon exercise of stock options, shares	25,494
Shares issued upon vesting of restricted stock units, value		100			100
Shares issued upon vesting of restricted stock units, shares	36,000
Net Loss			(30,745)		(30,745)
Other comprehensive loss				(17)	(17)
Balance, Value at Jun. 30, 2021	$ 50	$ 649,784	$ (446,363)	$ (5)	$ 203,466
Balance, Shares at Jun. 30, 2021	50,088,161