Condensed Consolidated Statement of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common stock	Treasury stock	Additional paid-in capital	Accumulated deficit
Balance, beginning of year at Dec. 31, 2020	$ (557)	$ 506	$ (260)	$ 558,059	$ (558,862)
Balance, beginning of year (in shares) at Dec. 31, 2020		50,712,151	72,727
Proceeds from follow-on offering, net of costs	39,226	$ 62		39,164
Proceeds from follow-on offering, net of costs (shares)		6,222,222
Stock-based compensation	3,163			3,163
Stock option exercises	51			51
Stock option exercises (in shares)		12,727
Employee stock purchase program (ESPP)	323	$ 1		322
Employee stock purchase program (ESPP) (in shares)		95,919
Vested restricted stock	758	$ 6		752
Vested restricted stock (in shares)		554,896
Shares withheld for tax obligations on vested RSUs	(1,215)	$ (1)		(1,214)
Shares withheld for tax obligations on vested RSUs, shares		(82,830)
Incurred net losses	(54,690)				(54,690)
Balance, end of year at Mar. 31, 2021	(12,941)	$ 574	$ (260)	600,297	(613,552)
Balance, end of year (in shares) at Mar. 31, 2021		57,515,085	72,727
Balance, beginning of year at Dec. 31, 2020	(557)	$ 506	$ (260)	558,059	(558,862)
Balance, beginning of year (in shares) at Dec. 31, 2020		50,712,151	72,727
Incurred net losses	(74,824)
Balance, end of year at Jun. 30, 2021	(30,876)	$ 579	$ (260)	602,491	(633,686)
Balance, end of year (in shares) at Jun. 30, 2021		57,929,094	72,727
Balance, beginning of year at Mar. 31, 2021	(12,941)	$ 574	$ (260)	600,297	(613,552)
Balance, beginning of year (in shares) at Mar. 31, 2021		57,515,085	72,727
Stock-based compensation	2,584			2,584
Stock option exercises	95	$ 1		94
Stock option exercises (in shares)		23,636
Vested restricted stock	247	$ 5		242	0
Vested restricted stock (in shares)		471,759
Shares withheld for tax obligations on vested RSUs	(727)	$ (1)		(726)
Shares withheld for tax obligations on vested RSUs, shares		(81,386)
Incurred net losses	(20,134)				(20,134)
Balance, end of year at Jun. 30, 2021	(30,876)	$ 579	$ (260)	602,491	(633,686)
Balance, end of year (in shares) at Jun. 30, 2021		57,929,094	72,727
Balance, beginning of year at Dec. 31, 2021	40,857	$ 622	$ (260)	661,839	(621,344)
Balance, beginning of year (in shares) at Dec. 31, 2021		62,242,090	72,727
Stock-based compensation	2,196			2,196
Employee stock purchase program (ESPP)	329	$ 1		328
Employee stock purchase program (ESPP) (in shares)		139,574
Vested restricted stock		$ 3		(3)
Vested restricted stock (in shares)		265,331
Shares withheld for tax obligations on vested RSUs	(255)	$ (1)		(254)
Shares withheld for tax obligations on vested RSUs, shares		(94,068)
Incurred net losses	(18,041)				(18,041)
Balance, end of year at Mar. 31, 2022	25,086	$ 625	$ (260)	664,106	(639,385)
Balance, end of year (in shares) at Mar. 31, 2022		62,552,927	72,727
Balance, beginning of year at Dec. 31, 2021	40,857	$ 622	$ (260)	661,839	(621,344)
Balance, beginning of year (in shares) at Dec. 31, 2021		62,242,090	72,727
Incurred net losses	(36,345)
Balance, end of year at Jun. 30, 2022	8,669	$ 627	$ (260)	665,991	(657,689)
Balance, end of year (in shares) at Jun. 30, 2022		62,796,204	72,727
Balance, beginning of year at Mar. 31, 2022	25,086	$ 625	$ (260)	664,106	(639,385)
Balance, beginning of year (in shares) at Mar. 31, 2022		62,552,927	72,727
Stock-based compensation	2,062			2,062
Vested restricted stock		$ 3		(3)
Vested restricted stock (in shares)		330,770
Shares withheld for tax obligations on vested RSUs	(175)	$ (1)		(174)
Shares withheld for tax obligations on vested RSUs, shares		(87,493)
Incurred net losses	(18,304)				(18,304)
Balance, end of year at Jun. 30, 2022	$ 8,669	$ 627	$ (260)	$ 665,991	$ (657,689)
Balance, end of year (in shares) at Jun. 30, 2022		62,796,204	72,727