Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balances (in shares) at Dec. 31, 2019		163,274,880
Balances at Dec. 31, 2019	$ 71,711	$ 0	$ 1,752,048	$ (27,468)	$ (1,652,869)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	13,869		13,869
Shares issued upon vesting of restricted stock units and for exercises of stock options (in shares)		868,857
Shares issued upon vesting of restricted stock units and for exercises of stock options	69		69
Shares issued for accrued compensation (in shares)		1,880,405
Shares issued for accrued compensation	5,100		5,100
Shares issued as payment for services (in shares)		413,911
Shares issued as payment for services	1,006		1,006
Shares issued upon conversion of long-term debt (in shares)		6,293,402
Shares issued upon conversion of long-term debt	31,827		31,827
Shares issued in private placement or in public offering, net of issuance costs (in shares)		5,972,696
Shares issued in private placement or in public offering, net of issuance costs	35,000		35,000
Net loss	(128,860)				(128,860)
Release of cumulative translation adjustments to loss from discontinued operations	26,957			26,957
Other comprehensive income (loss)	1,873			1,873
Balances (in shares) at Sep. 30, 2020		178,704,151
Balances at Sep. 30, 2020	58,552	$ 0	1,838,919	1,362	(1,781,729)
Balances (in shares) at Jun. 30, 2020		172,285,932
Balances at Jun. 30, 2020	49,542	$ 0	1,802,413	(650)	(1,752,221)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	4,600		4,600
Shares issued upon vesting of restricted stock units and for exercises of stock options (in shares)		28,389
Shares issued upon vesting of restricted stock units and for exercises of stock options	3		3
Shares issued for accrued compensation (in shares)		75,000
Shares issued for accrued compensation	0
Shares issued as payment for services (in shares)		21,428
Shares issued as payment for services	76		76
Shares issued upon conversion of long-term debt (in shares)		6,293,402
Shares issued upon conversion of long-term debt	31,827		31,827
Net loss	(29,508)				(29,508)
Release of cumulative translation adjustments to loss from discontinued operations	0
Other comprehensive income (loss)	2,012			2,012
Balances (in shares) at Sep. 30, 2020		178,704,151
Balances at Sep. 30, 2020	$ 58,552	$ 0	1,838,919	1,362	(1,781,729)
Balances (in shares) at Dec. 31, 2020	187,663,207	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	11,462		11,462
Shares issued upon vesting of restricted stock units and for exercises of stock options (in shares)		1,750,521
Shares issued upon vesting of restricted stock units and for exercises of stock options	603		603
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 loss	(67,132)				(67,132)
Release of cumulative translation adjustments to loss from discontinued operations	0
Other comprehensive income (loss)	$ (2,482)			(2,482)
Balances (in shares) at Sep. 30, 2021	206,738,499	206,738,499
Balances at Sep. 30, 2021	$ 131,247	$ 0	2,020,254	1,515	(1,890,522)
Balances (in shares) at Jun. 30, 2021		206,580,928
Balances at Jun. 30, 2021	159,196	$ 0	2,017,413	2,541	(1,860,758)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation expense	2,490		2,490
Shares issued upon vesting of restricted stock units and for exercises of stock options (in shares)		157,571
Shares issued upon vesting of restricted stock units and for exercises of stock options	351		351
Net loss	(29,764)				(29,764)
Release of cumulative translation adjustments to loss from discontinued operations	0
Other comprehensive income (loss)	$ (1,026)			(1,026)
Balances (in shares) at Sep. 30, 2021	206,738,499	206,738,499
Balances at Sep. 30, 2021	$ 131,247	$ 0	$ 2,020,254	$ 1,515	$ (1,890,522)