Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative effect of adoption of ASU 2020-06	Common Stock	Additional Paid-in Capital	Additional Paid-in Capital Cumulative effect of adoption of ASU 2020-06	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated Deficit Cumulative effect of adoption of ASU 2020-06
Balances (in shares) at Dec. 31, 2021			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
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2020-06 [Member]
Balances (in shares) at Mar. 31, 2022			207,693,277
Balances at Mar. 31, 2022	$ 73,836		$ 0	1,991,670		(1,699)	(1,916,135)
Balances (in shares) at Dec. 31, 2021			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	5,871			5,871
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)			772,071
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 loss	(36,886)						(36,886)
Other comprehensive income (loss)	(4,759)					(4,759)
Balances (in shares) at Jun. 30, 2022			208,150,021
Balances at Jun. 30, 2022	55,653		$ 0	1,993,979		(4,556)	(1,933,770)
Balances (in shares) at Mar. 31, 2022			207,693,277
Balances at Mar. 31, 2022	73,836		$ 0	1,991,670		(1,699)	(1,916,135)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	2,309			2,309
Shares issued for accrued compensation (in shares)			456,744
Shares issued for accrued compensation	0			0
Net loss	(17,635)						(17,635)
Other comprehensive income (loss)	(2,857)					(2,857)
Balances (in shares) at Jun. 30, 2022			208,150,021
Balances at Jun. 30, 2022	$ 55,653		$ 0	1,993,979		(4,556)	(1,933,770)
Balances (in shares) at Dec. 31, 2022	208,150,021		208,150,021
Balances at Dec. 31, 2022	$ 126,259		$ 0	1,998,314		(3,488)	(1,868,567)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	5,320			5,320
Shares issued upon vesting of restricted stock units and for exercises of stock options (in shares)			697,815
Shares issued upon vesting of restricted stock units and for exercises of stock options	0			0
Shares issued for accrued compensation (in shares)			2,206,469
Shares issued for accrued compensation	3,361			3,361
Shares issued as payment for services (in shares)			465,808
Shares issued as payment for services	545			545
Shares issued in private placement or in public offering, net of issuance costs (in shares)			43,962,640
Shares issued in private placement or in public offering, net of issuance costs	72,808			72,808
Net loss	(43,053)						(43,053)
Other comprehensive income (loss)	$ 970					970
Balances (in shares) at Jun. 30, 2023	255,482,753		255,482,753
Balances at Jun. 30, 2023	$ 166,210		$ 0	2,080,348		(2,518)	(1,911,620)
Balances (in shares) at Mar. 31, 2023			255,482,753
Balances at Mar. 31, 2023	184,133		$ 0	2,078,133		(2,699)	(1,891,301)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	2,188			2,188
Other	27			27
Net loss	(20,319)						(20,319)
Other comprehensive income (loss)	$ 181					181
Balances (in shares) at Jun. 30, 2023	255,482,753		255,482,753
Balances at Jun. 30, 2023	$ 166,210		$ 0	$ 2,080,348		$ (2,518)	$ (1,911,620)