Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2018	$ 66,592	$ 19	$ 237,795	$ (25)	$ (171,197)
Beginning Balance, Shares at Dec. 31, 2018		19,211,759
Issuance of common stock upon public offering, net of issuance costs	53,194	$ 5	53,189
Issuance of common stock upon public offering, net of issuance costs, shares		5,175,000
Issuance of common stock upon ESPP purchase	130		130
Issuance of common stock upon ESPP purchase, Shares		15,701
Issuance of common stock upon stock option exercise	844		844
Issuance of common stock upon stock option exercises, Shares		120,921
Issuance of common stock under Product Development Agreement	226		226
Stock-based compensation expense	5,679		5,679
Unrealized (loss) gain on available-for-sale debt securities, net	67			67
Net loss	(70,252)				(70,252)
Ending Balance at Dec. 31, 2019	56,480	$ 24	297,863	42	(241,449)
Ending Balance, Shares at Dec. 31, 2019		24,523,381
Issuance of common stock upon public offering, net of issuance costs	96,760	$ 10	96,750
Issuance of common stock upon public offering, net of issuance costs, shares		9,267,760
Issuance of common stock upon ESPP purchase	186		186
Issuance of common stock upon ESPP purchase, Shares		25,645
Issuance of common stock upon stock option exercise	520		520
Issuance of common stock upon stock option exercises, Shares		61,700
Issuance of common stock under Product Development Agreement	217		217
Stock-based compensation expense	5,973		5,973
Unrealized (loss) gain on available-for-sale debt securities, net	(50)			(50)
Net loss	(65,051)				(65,051)
Ending Balance at Dec. 31, 2020	$ 95,035	$ 34	401,509	(8)	(306,500)
Ending Balance, Shares at Dec. 31, 2020	33,878,486	33,878,486
Issuance of common stock upon public offering, net of issuance costs	$ 2,685	$ 1	2,684
Issuance of common stock upon public offering, net of issuance costs, shares		565,938
Issuance of common stock upon ESPP purchase	257		257
Issuance of common stock upon ESPP purchase, Shares		37,619
Issuance of common stock upon stock option exercise	$ 361		361
Issuance of common stock upon stock option exercises, Shares	53,028	53,028
Issuance of common stock upon release of restricted stock units, Shares		33,750
Issuance of common stock under Product Development Agreement	$ 218		218
Stock-based compensation expense	7,901		7,901
Unrealized (loss) gain on available-for-sale debt securities, net	(141)			(141)
Net loss	(33,917)				(33,917)
Ending Balance at Dec. 31, 2021	$ 72,399	$ 35	$ 412,930	$ (149)	$ (340,417)
Ending Balance, Shares at Dec. 31, 2021	34,568,821	34,568,821