Consolidated Statements 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, 2018	$ 66,878	$ 286	$ (260)	$ 428,949	$ (362,097)
Balance, beginning of year (in shares) at Dec. 31, 2018		28,701,494	72,727
Proceeds from follow-on offering, net of costs	107,734	$ 200		107,534
Proceeds from follow-on offering, net of costs (in shares)		20,000,000
Employee stock-based compensation expense	12,655			12,655
Stock option exercises	125			125
Stock option exercises (in shares)		51,451
Employee stock purchase program (ESPP)	1,216	$ 1		1,215
Employee stock purchase program (ESPP) (in shares)		175,624
Vested restricted stock		$ 10		(10)
Vested restricted stock (in shares)		944,467
Shares withheld for tax obligations on vested RSUs	(3,064)	$ (2)		(3,062)
Shares withheld for tax obligations on vested RSUs, shares		(260,129)
Equity contingent consideration	3,156			3,156
Net loss	(106,818)				(106,818)
Balance, end of year at Dec. 31, 2019	81,882	$ 495	$ (260)	550,562	(468,915)
Balance, end of year (in shares) at Dec. 31, 2019		49,612,907	72,727
Proceeds from follow-on offering, net of costs	263			263
Proceeds from follow-on offering, net of costs (in shares)		37,000
Employee stock-based compensation expense	8,171			8,171
Stock option exercises	29			29
Stock option exercises (in shares)		9,817
Employee stock purchase program (ESPP)	836	$ 2		834
Employee stock purchase program (ESPP) (in shares)		203,728
Vested restricted stock		$ 12		(12)
Vested restricted stock (in shares)		1,150,707
Shares withheld for tax obligations on vested RSUs	(1,791)	$ (3)		(1,788)
Shares withheld for tax obligations on vested RSUs, shares		(302,008)
Net loss	(89,947)				(89,947)
Balance, end of year at Dec. 31, 2020	(557)	$ 506	$ (260)	558,059	(558,862)
Balance, end 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 (in shares)		6,222,222
Employee stock-based compensation expense	10,390			10,390
Stock option exercises	291			290
Stock option exercises (in shares)		72,726
Employee stock purchase program (ESPP)	674	$ 2		672
Employee stock purchase program (ESPP) (in shares)		199,071
Vested restricted stock	1,005	$ 15		990
Vested restricted stock (in shares)		1,452,893
Shares withheld for tax obligations on vested RSUs	(3,145)	$ (3)		(3,142)
Shares withheld for tax obligations on vested RSUs, shares		(347,628)
Shares issued for asset acquisition	14,425	$ 39		14,386
Shares issued for asset acquisition (in shares)		3,930,655
Reclassification of derivative liability to equity	41,030			41,030
Net loss	(62,482)				(62,482)
Balance, end of year at Dec. 31, 2021	$ 40,857	$ 622	$ (260)	$ 661,839	$ (621,344)
Balance, end of year (in shares) at Dec. 31, 2021		62,242,090	72,727