Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ 12,895	$ 10	$ 284,313	$ (271,428)
Beginning balance (in shares) at Dec. 31, 2019		9,741,372
Net loss	(55,185)			(55,185)
Stock-based compensation expense	2,220		2,220
Common stock issued through employee stock purchase and stock option plans	28		28
Common stock issued through employee stock purchase plan and stock option plan (in shares)		4,652
Common stock issued, net of expenses	57,184	$ 9	57,175
Common stock issued, net of expenses (in shares)		9,156,304
Common stock issued for conversion	5,222	$ 1	5,221
Common stock issued for conversion of Notes (in shares)		638,809
Common stock issued for Commitment Shares	602		602
Common stock issued for Commitment Shares (in shares)		70,910
Common stock issued for vested restricted stock units	(208)		(208)
Common stock issued for vested restricted stock units (in shares)		51,651
Ending balance at Dec. 31, 2020	$ 22,758	$ 20	349,351	(326,613)
Ending balance (in shares) at Dec. 31, 2020	19,663,698	19,663,698
Net loss	$ (32,866)			(32,866)
Stock-based compensation expense	2,088		2,088
Common stock issued through employee stock purchase and stock option plans	22		22
Common stock issued through employee stock purchase plan and stock option plan (in shares)		4,943
Common stock issued, net of expenses	41,040	$ 11	41,029
Common stock issued, net of expenses (in shares)		8,067,562
Common stock issued for conversion	7,453	$ 1	7,452
Common stock issued for conversion of Notes (in shares)		959,080
Common stock issued for vested restricted stock units	(3)		(3)
Common stock issued for vested restricted stock units (in shares)		10,051
Vested Loan Agreement warrants	766		766
Ending balance at Dec. 31, 2021	$ 41,258	$ 32	$ 400,705	$ (359,479)
Ending balance (in shares) at Dec. 31, 2021	28,705,334	28,705,334