Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands		Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balances at Dec. 31, 2020		$ 64,383	$ 55	$ 320,893	$ (257,507)	$ 942
Beginning balance, shares at Dec. 31, 2020			54,152,955
Issuance of common stock and pre-funded warrants in public offering, net of offering costs	[1]	121,827	$ 57	121,770
Issuance of common stock and pre-funded warrants, shares	[1]		57,479,978
Repurchase of outstanding pre-funded warrants		(3,909)		(3,909)
Net issuance of common stock upon exercise of stock warrants, net		2,546	$ 2	2,544
Net issuance of common stock upon exercise of stock warrants, net, shares			1,737,450
Issuance of common stock for settlement of RSUs, shares			5,563
Issuance of common stock upon exercise of stock options		2		2
Issuance of common stock upon exercise of stock options, shares			202,708
Stock-based compensation		946		946
Foreign exchange translation adjustment		(431)				(431)
Unrealized gain (loss) on short-term investments		(26)				(26)
Net loss		(10,217)			(10,217)
Ending balances at Mar. 31, 2021		175,121	$ 114	442,246	(267,724)	485
Ending balance, shares at Mar. 31, 2021			113,578,654
Beginning balances at Dec. 31, 2020		64,383	$ 55	320,893	(257,507)	942
Beginning balance, shares at Dec. 31, 2020			54,152,955
Foreign exchange translation adjustment		(348)
Unrealized gain (loss) on short-term investments		(2)
Net loss		(21,158)
Ending balances at Jun. 30, 2021		165,382	$ 114	443,341	(278,665)	592
Ending balance, shares at Jun. 30, 2021			113,847,532
Beginning balances at Mar. 31, 2021		175,121	$ 114	442,246	(267,724)	485
Beginning balance, shares at Mar. 31, 2021			113,578,654
Issuance of common stock and pre-funded warrants in public offering, net of offering costs		321		321
Issuance of common stock for settlement of RSUs, shares			203,687
Issuance of common stock upon exercise of stock options		3		3
Issuance of common stock upon exercise of stock options, shares			65,191
Stock-based compensation		771		771
Foreign exchange translation adjustment		83				83
Unrealized gain (loss) on short-term investments		24				24
Net loss		(10,941)			(10,941)
Ending balances at Jun. 30, 2021		165,382	$ 114	443,341	(278,665)	592
Ending balance, shares at Jun. 30, 2021			113,847,532
Beginning balances at Dec. 31, 2021		$ 144,498	$ 116	444,898	(300,521)	5
Beginning balance, shares at Dec. 31, 2021		114,036,892	114,036,892
Repurchase of shares for minimum tax withholdings		$ (1)		(1)
Repurchase of shares for minimum tax withholdings, shares			(720)
Issuance of common stock for settlement of RSUs, shares			3,688
Stock-based compensation		574		574
Foreign exchange translation adjustment		(208)				(208)
Unrealized gain (loss) on short-term investments		(88)				(88)
Net loss		(8,300)			(8,300)
Ending balances at Mar. 31, 2022		136,475	$ 116	445,471	(308,821)	(291)
Ending balance, shares at Mar. 31, 2022			114,039,860
Beginning balances at Dec. 31, 2021		$ 144,498	$ 116	444,898	(300,521)	5
Beginning balance, shares at Dec. 31, 2021		114,036,892	114,036,892
Issuance of common stock for settlement of RSUs, shares		5,500
Issuance of common stock upon exercise of stock options, shares		0
Foreign exchange translation adjustment		$ (953)
Unrealized gain (loss) on short-term investments		(68)
Net loss		(17,464)
Ending balances at Jun. 30, 2022		$ 127,042	$ 116	445,927	(317,985)	(1,016)
Ending balance, shares at Jun. 30, 2022		114,041,271	114,041,271
Beginning balances at Mar. 31, 2022		$ 136,475	$ 116	445,471	(308,821)	(291)
Beginning balance, shares at Mar. 31, 2022			114,039,860
Repurchase of shares for minimum tax withholdings, shares			(401)
Issuance of common stock for settlement of RSUs, shares			1,812
Stock-based compensation		456		456
Foreign exchange translation adjustment		(745)				(745)
Unrealized gain (loss) on short-term investments		20				20
Net loss		(9,164)			(9,164)
Ending balances at Jun. 30, 2022		$ 127,042	$ 116	$ 445,927	$ (317,985)	$ (1,016)
Ending balance, shares at Jun. 30, 2022		114,041,271	114,041,271

[1] As discussed in Note 8. Stockholders’ Equity, the Company sold (i) an aggregate of 57,479,978 shares of the Company’s common stock, par value $0.001 per share and (ii) pre-funded warrants to purchase an aggregate of 32,175,172 shares of the Company's common stock at an exercise price, equal to the par value, of $0.001 per share.