Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2019	$ 80,048	$ 48	$ 396,278	$ 1	$ (316,279)
Beginning balance, units at Dec. 31, 2019		48,283,270
Equity-based compensation	9,111		9,111
Vesting of restricted stock, units		284,700
Forfeiture of restricted stock awards units		(93,752)
Unrealized loss on available-for-sale securities	(1)			(1)
Net loss	(66,927)				(66,927)
Ending balance at Sep. 30, 2020	22,231	$ 48	405,389		(383,206)
Ending balance, units at Sep. 30, 2020		48,474,218
Beginning balance at Jun. 30, 2020	40,713	$ 48	402,625		(361,960)
Beginning balance, units at Jun. 30, 2020		48,364,092
Equity-based compensation	2,764		2,764
Vesting of restricted stock, units		162,725
Forfeiture of restricted stock awards units		(52,599)
Unrealized loss on available-for-sale securities	0
Net loss	(21,246)				(21,246)
Ending balance at Sep. 30, 2020	22,231	$ 48	405,389		(383,206)
Ending balance, units at Sep. 30, 2020		48,474,218
Beginning balance at Dec. 31, 2020	132,086	$ 87	536,568		(404,569)
Beginning balance, units at Dec. 31, 2020		87,052,323
Equity-based compensation	9,958		9,958
Sale of common stock, net of issuance costs	134,878	$ 25	134,853
Sale of common stock, net of issuance costs, shares		25,000,000
Exercise of stock options	41		41
Exercise of stock options, shares		11,625
Vesting of restricted stock, units		419,193
Forfeiture of restricted stock awards units		(29,212)
Unrealized loss on available-for-sale securities	(22)			(22)
Net loss	(53,578)				(53,578)
Ending balance at Sep. 30, 2021	223,363	$ 112	681,420	(22)	(458,147)
Ending balance, units at Sep. 30, 2021		112,453,929
Beginning balance at Jun. 30, 2021	237,938	$ 112	678,001	(11)	(440,164)
Beginning balance, units at Jun. 30, 2021		112,454,321
Equity-based compensation	3,416		3,416
Exercise of stock options	3		3
Exercise of stock options, shares		1,000
Forfeiture of restricted stock awards units		(1,392)
Unrealized loss on available-for-sale securities	(11)			(11)
Net loss	(17,983)				(17,983)
Ending balance at Sep. 30, 2021	$ 223,363	$ 112	$ 681,420	$ (22)	$ (458,147)
Ending balance, units at Sep. 30, 2021		112,453,929