Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Balances (in shares) at Dec. 31, 2020			187,663,207
Balances at Dec. 31, 2020	$ 67,174		$ 0	$ 1,886,567		$ 3,997	$ (1,823,390)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	5,415			5,415
Shares issued upon vesting of restricted stock units and for exercises of stock options (in shares)			1,426,157
Shares issued upon vesting of restricted stock units and for exercises of stock options	153			153
Shares issued as payment for services (in shares)			74,771
Shares issued as payment for services	$ 577			577
Shares issued in private placement or in public offering, net of issuance costs (in shares)	17,250,000
Shares issued in private placement or in public offering, net of issuance costs	$ 121,045			121,045
Net Income (Loss) Attributable to Parent	(17,318)						(17,318)
Other comprehensive income (loss)	(2,251)					(2,251)
Balances (in shares) at Mar. 31, 2021			206,414,135
Balances at Mar. 31, 2021	$ 174,795		$ 0	2,013,757		1,746	(1,840,708)
Balances (in shares) at Dec. 31, 2021	206,739,874		206,739,874
Balances at Dec. 31, 2021	$ 107,348	$ (18,196)	$ 0	2,022,701	$ (36,868)	203	(1,915,556)	$ 18,672
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	3,562			3,562
Shares issued upon vesting of restricted stock units and for exercises of stock options (in shares)			354,089
Shares issued upon vesting of restricted stock units and for exercises of stock options	1			1
Shares issued for accrued compensation (in shares)			315,327
Shares issued for accrued compensation	1,698			1,698
Shares issued as payment for services (in shares)			283,987
Shares issued as payment for services	576			576
Net Income (Loss) Attributable to Parent	(19,251)						(19,251)
Other comprehensive income (loss)	$ (1,902)					(1,902)
Balances (in shares) at Mar. 31, 2022	207,693,277		207,693,277
Balances at Mar. 31, 2022	$ 73,836		$ 0	$ 1,991,670		$ (1,699)	$ (1,916,135)
Increase (Decrease) in Stockholders' Equity
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2020-06 [Member]