Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	ATM Program [Member] Common Stock [Member]	ATM Program [Member] Additional Paid-in Capital [Member]	ATM Program [Member] Retained Earnings [Member]	ATM Program [Member] Treasury Stock [Member]	ATM Program [Member]	Share Purchase Agreement, December 2019 [Member] Common Stock [Member]	Share Purchase Agreement, December 2019 [Member] Additional Paid-in Capital [Member]	Share Purchase Agreement, December 2019 [Member] Retained Earnings [Member]	Share Purchase Agreement, December 2019 [Member] Treasury Stock [Member]	Share Purchase Agreement, December 2019 [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2019											13,697
Balance at Dec. 31, 2019											$ 14	$ 763,097	$ (685,122)	$ (3,054)	$ 74,935
Net loss													(32,566)		(32,566)
Issuance of common stock and common stock warrants, net of issuance costs (in shares)											3,172
Issuance of common stock and common stock warrants, net of issuance costs											$ 3	20,243			20,246
Modification of warrants												1,112			1,112
Vesting of restricted stock units (in shares)											35
Vesting of restricted stock units															0
Exercise of common stock warrants (in shares)											18
Exercise of common stock warrants												141			141
Stock-based compensation expense												5,684			5,684
Balance (in shares) at Dec. 31, 2020											16,922
Balance at Dec. 31, 2020											$ 17	790,277	(717,688)	$ (3,054)	69,552
Net loss													(67,636)		(67,636)
Issuance of common stock and common stock warrants, net of issuance costs (in shares)											9,230
Issuance of common stock and common stock warrants, net of issuance costs											$ 9	27,381			27,390
Stock-based compensation expense												7,238			7,238
Issuance of common stock, ATM Program, net of issuance costs (in shares)	2,117
Issuance of common stock, ATM Program, net of issuance costs	$ 2	$ 4,841			$ 4,843
Issuance of common stock warrants, equity consideration for service agreement							$ 494			$ 494
Balance (in shares) at Dec. 31, 2021											28,269
Balance at Dec. 31, 2021											$ 28	$ 830,231	$ (785,324)	$ (3,054)	$ 41,881