Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	IPO [Member]	Common Stock [Member]	Common Stock [Member] IPO [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] IPO [Member]	Accumulated Deficit [Member]
Balances at beginning at Dec. 31, 2019	$ 14,947		$ 45		$ 172,708		$ (157,806)
Balances at beginning (shares) at Dec. 31, 2019			44,658,054
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	392				392
Issuance of common stock under equity incentive plan (shares)			28,757
Net loss	(5,858)						(5,858)
Balances at ending at Mar. 31, 2020	9,481		$ 45		173,100		(163,664)
Balances at end (shares) at Mar. 31, 2020			44,686,811
Balances at beginning at Dec. 31, 2019	14,947		$ 45		172,708		(157,806)
Balances at beginning (shares) at Dec. 31, 2019			44,658,054
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(13,242)
Balances at ending at Jun. 30, 2020	56,177		$ 80		227,145		(171,048)
Balances at end (shares) at Jun. 30, 2020			79,560,274
Balances at beginning at Mar. 31, 2020	9,481		$ 45		173,100		(163,664)
Balances at beginning (shares) at Mar. 31, 2020			44,686,811
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	341				341
Issuance of common stock under equity incentive plan	17				17
Issuance of common stock under equity incentive plan (shares)			24,979
Sale of common stock in public offering, net of costs of $3,778		$ 53,722		$ 35		$ 53,687
Sale of common stock in public offering, net of costs, (shares)				34,848,484
Net loss	(7,384)						(7,384)
Balances at ending at Jun. 30, 2020	56,177		$ 80		227,145		(171,048)
Balances at end (shares) at Jun. 30, 2020			79,560,274
Balances at beginning at Dec. 31, 2020	45,547		$ 80		227,912		(182,445)
Balances at beginning (shares) at Dec. 31, 2020			79,615,692
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,095				1,095
Issuance of common stock under equity incentive plan (shares)			167,060
Tax withholding payments for net share-settled equity awards	(120)				(120)
Tax withholding payments for net share-settled equity awards (shares)			(59,072)
Net loss	(8,954)						(8,954)
Balances at ending at Mar. 31, 2021	37,568		$ 80		228,887		(191,399)
Balances at end (shares) at Mar. 31, 2021			79,723,680
Balances at beginning at Dec. 31, 2020	45,547		$ 80		227,912		(182,445)
Balances at beginning (shares) at Dec. 31, 2020			79,615,692
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(19,942)
Balances at ending at Jun. 30, 2021	27,437		$ 80		229,744		(202,387)
Balances at end (shares) at Jun. 30, 2021			79,759,225
Balances at beginning at Mar. 31, 2021	37,568		$ 80		228,887		(191,399)
Balances at beginning (shares) at Mar. 31, 2021			79,723,680
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	857				857
Issuance of common stock under equity incentive plan (shares)			35,545
Net loss	(10,988)						(10,988)
Balances at ending at Jun. 30, 2021	$ 27,437		$ 80		$ 229,744		$ (202,387)
Balances at end (shares) at Jun. 30, 2021			79,759,225