Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2019	14,083,232
Balance at Dec. 31, 2019	$ 141	$ 530,349	$ (457,986)	$ 72,504
Issuance of common stock, net of issue costs (in shares)	425,776
Issuance of common stock, net of issue costs	$ 4	902		906
Non-cash stock-based compensation		336		336
Issuance of common stock under stock plans, net of taxes (in shares)	105,882
Issuance of common stock under stock plans, net of taxes
Net loss			(9,253)	(9,253)
Balance (in shares) at Mar. 31, 2020	14,614,890
Balance at Mar. 31, 2020	$ 145	531,587	(467,239)	64,493
Balance (in shares) at Dec. 31, 2020	128,138,311
Balance at Dec. 31, 2020	$ 1,282	643,269	(498,172)	146,379
Issuance of common stock, net of issue costs (in shares)	68,170,579
Issuance of common stock, net of issue costs	$ 682	457,008		457,690
Issuance of common stock upon exercise of warrants (in shares)	1,863,058
Issuance of common stock upon exercise of warrants	$ 18	1,099		1,117
Non-cash stock-based compensation		562		562
Issuance of common stock under stock plans, net of taxes (in shares)	(121,499)
Issuance of common stock under stock plans, net of taxes	$ (1)	1
Net loss			(10,057)	(10,057)
Balance (in shares) at Mar. 31, 2021	198,050,449
Balance at Mar. 31, 2021	$ 1,981	$ 1,101,939	$ (508,229)	$ 595,691