CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Gain (Loss)
Balances at Dec. 31, 2021	$ 126,416	$ 324	$ 1,398,006	$ (1,271,741)	$ (173)
Balances (in shares) at Dec. 31, 2021		323,731,591
Increase (Decrease) in Stockholders' Equity
Net loss	(30,098)			(30,098)
Other comprehensive income (loss)	(539)				(539)
Foreign currency translation adjustment	1				1
Stock-based compensation related to issuance of common stock and options in exchange for services	15		15
Stock-based compensation related to issuance of common stock and options in exchange for services (in shares)		5,284
Stock-based compensation for equity-based awards to employees and directors	1,692		1,692
Balances at Mar. 31, 2022	97,487	$ 324	1,399,713	(1,301,839)	(711)
Balances (in shares) at Mar. 31, 2022		323,736,875
Balances at Dec. 31, 2021	126,416	$ 324	1,398,006	(1,271,741)	(173)
Balances (in shares) at Dec. 31, 2021		323,731,591
Increase (Decrease) in Stockholders' Equity
Net loss	(58,215)
Other comprehensive income (loss)	(621)
Foreign currency translation adjustment	12
Balances at Jun. 30, 2022	142,047	$ 378	1,472,407	(1,329,956)	(782)
Balances (in shares) at Jun. 30, 2022		377,664,759
Balances at Mar. 31, 2022	97,487	$ 324	1,399,713	(1,301,839)	(711)
Balances (in shares) at Mar. 31, 2022		323,736,875
Increase (Decrease) in Stockholders' Equity
Net loss	(28,117)			(28,117)
Other comprehensive income (loss)	(82)				(82)
Foreign currency translation adjustment	11				11
Issuance of common stock and pre-funded warrant to purchase common stock in public offering, net of issuance costs	69,916	$ 53	69,863
Issuance of common stock and pre-funded warrant to purchase common stock in public offering, net of issuance costs (in shares)		53,333,334
Stock-based compensation related to issuance of common stock and options in exchange for services	13		13
Stock-based compensation related to issuance of common stock and options in exchange for services (in shares)		4,637
Issuance of common stock under equity plans	761	$ 1	760
Issuance of common stock under equity plans (in shares)		589,913
Stock-based compensation for equity-based awards to employees and directors	2,058		2,058
Balances at Jun. 30, 2022	142,047	$ 378	1,472,407	(1,329,956)	(782)
Balances (in shares) at Jun. 30, 2022		377,664,759
Balances at Dec. 31, 2022	79,998	$ 390	1,493,469	(1,413,642)	(219)
Balances (in shares) at Dec. 31, 2022		390,262,524
Increase (Decrease) in Stockholders' Equity
Net loss	(38,122)			(38,122)
Other comprehensive income (loss)	75				75
Foreign currency translation adjustment	(16)				(16)
Issuance of common stock and pre-funded warrant to purchase common stock in public offering, net of issuance costs	213,337	$ 68	213,269
Issuance of common stock and pre-funded warrant to purchase common stock in public offering, net of issuance costs (in shares)		68,007,741
Issuance of common stock in connection with exercise of warrants	59,835	$ 45	59,790
Issuance of common stock in connection exercise of warrants (in shares)		44,983,193
Stock-based compensation related to issuance of common stock and options in exchange for services	112	$ 1	111
Stock-based compensation related to issuance of common stock and options in exchange for services (in shares)		9,360
Issuance of common stock under equity plans	7,875	$ 5	7,870
Issuance of common stock under equity plans (in shares)		5,469,028
Stock-based compensation for equity-based awards to employees and directors	2,961		2,961
Balances at Mar. 31, 2023	326,055	$ 509	1,777,470	(1,451,764)	(160)
Balances (in shares) at Mar. 31, 2023		508,731,846
Balances at Dec. 31, 2022	79,998	$ 390	1,493,469	(1,413,642)	(219)
Balances (in shares) at Dec. 31, 2022		390,262,524
Increase (Decrease) in Stockholders' Equity
Net loss	(87,349)
Other comprehensive income (loss)	(711)
Foreign currency translation adjustment	(15)
Balances at Jun. 30, 2023	298,427	$ 522	1,799,841	(1,500,991)	(945)
Balances (in shares) at Jun. 30, 2023		521,942,104
Balances at Mar. 31, 2023	326,055	$ 509	1,777,470	(1,451,764)	(160)
Balances (in shares) at Mar. 31, 2023		508,731,846
Increase (Decrease) in Stockholders' Equity
Net loss	(49,227)			(49,227)
Other comprehensive income (loss)	(786)				(786)
Foreign currency translation adjustment	1				1
Issuance of common stock in connection with exercise of warrants	17,767	$ 13	17,754
Issuance of common stock in connection exercise of warrants (in shares)		12,842,857
Stock-based compensation related to issuance of common stock and options in exchange for services	99		99
Stock-based compensation related to issuance of common stock and options in exchange for services (in shares)		6,327
Issuance of common stock under equity plans	573		573
Issuance of common stock under equity plans (in shares)		361,074
Stock-based compensation for equity-based awards to employees and directors	3,945		3,945
Balances at Jun. 30, 2023	$ 298,427	$ 522	$ 1,799,841	$ (1,500,991)	$ (945)
Balances (in shares) at Jun. 30, 2023		521,942,104