Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2020	$ 25	$ 195,410	$ (1)	$ (172,540)	$ 22,894
Balance, shares at Dec. 31, 2020	25,550
Issuance of common stock as part of debt extinguishment and private investment, net of issuance costs	$ 3	49,938			49,941
Issuance of common stock as part of debt extinguishment and private investment, net of issuance cost of $106, shares	3,049
Issuance of common stock, net of issuance costs		7,432			7,432
Issuance of common stock, net of issuance costs, shares	288
Issuance of common stock upon exercise of stock options		508			508
Issuance of common stock upon exercise of stock options, shares	45
Issuance of common stock under employee stock purchase plan		421			421
Issuance of common stock under employee stock purchase plan, shares	67
Issuance of common stock pursuant to warrant exercise	$ 1	3,333			3,334
Issuance of common stock pursuant to warrant exercise, shares	585
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes		(232)			(232)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares	22
Stock-based compensation expense		9,413			9,413
Unrealized gain on available-for-sale securities			$ 1		1
Net loss				(33,962)	(33,962)
Balance at Jun. 30, 2021	$ 29	266,223		(206,502)	59,750
Balance, shares at Jun. 30, 2021	29,606
Balance at Mar. 31, 2021	$ 26	211,550		(191,179)	20,397
Balance, shares at Mar. 31, 2021	26,401
Issuance of common stock as part of debt extinguishment and private investment, net of issuance costs	$ 3	49,938			49,941
Issuance of common stock as part of debt extinguishment and private investment, net of issuance cost of $106, shares	3,049
Issuance of common stock, net of issuance costs		2,469			2,469
Issuance of common stock, net of issuance costs, shares	131
Issuance of common stock upon exercise of stock options		59			59
Issuance of common stock upon exercise of stock options, shares	5
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes		(232)			(232)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares	22
Adjustment to shares issued under employee stock purchase plan		(9)			(9)
Adjustment to shares issued under employee stock purchase plan, shares	(2)
Stock-based compensation expense		2,448			2,448
Net loss				(15,323)	(15,323)
Balance at Jun. 30, 2021	$ 29	266,223		(206,502)	59,750
Balance, shares at Jun. 30, 2021	29,606
Balance at Dec. 31, 2021	$ 29	271,861		(236,200)	$ 35,690
Balance, shares at Dec. 31, 2021	29,716				29,716
Issuance of common stock, net of issuance costs	$ 7	14,882			$ 14,889
Issuance of common stock, net of issuance costs, shares	7,317
Issuance of common stock under employee stock purchase plan		372			372
Issuance of common stock under employee stock purchase plan, shares	86
Issuance of common stock pursuant to warrant exercise	$ 1	12			13
Issuance of common stock pursuant to warrant exercise, shares	7
Stock-based compensation expense		3,720			3,720
Net loss				(31,269)	(31,269)
Balance at Jun. 30, 2022	$ 37	290,847		(267,469)	$ 23,415
Balance, shares at Jun. 30, 2022	37,126				37,126
Balance at Mar. 31, 2022	$ 29	274,240		(253,473)	$ 20,796
Balance, shares at Mar. 31, 2022	29,802
Issuance of common stock, net of issuance costs	$ 7	14,882			14,889
Issuance of common stock, net of issuance costs, shares	7,317
Issuance of common stock pursuant to warrant exercise	$ 1	12			13
Issuance of common stock pursuant to warrant exercise, shares	7
Stock-based compensation expense		1,713			1,713
Net loss				(13,996)	(13,996)
Balance at Jun. 30, 2022	$ 37	$ 290,847		$ (267,469)	$ 23,415
Balance, shares at Jun. 30, 2022	37,126				37,126