CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Follow-on Public Offering	Common Stock	Common Stock Follow-on Public Offering	Additional Paid-in Capital	Additional Paid-in Capital Follow-on Public Offering	Accumulated Deficit
Beginning Balance at Dec. 31, 2019	$ 62,140		$ 2		$ 116,162		$ (54,024)
Beginning Balance, Shares at Dec. 31, 2019			14,968
Stock-based compensation expense	5,831				5,831
Net income (loss)	(10,696)						(10,696)
Issuance of common stock upon follow-on public offering net of underwriting discounts and commissions and other offering costs		$ 45,789				$ 45,789
Issuance of common stock upon follow-on public offering net of underwriting discounts and commissions and other offerings costs, Shares				1,525
Issuance of shares upon vesting of restricted stock units, net of tax withholdings	(3,495)				(3,495)
Issuance of shares upon vesting of restricted stock units, net of tax withholdings, Shares			223
Ending Balance at Jun. 30, 2020	99,569		$ 2		164,287		(64,720)
Ending Balance, Shares at Jun. 30, 2020			16,716
Beginning Balance at Mar. 31, 2020	58,014		$ 2		117,129		(59,117)
Beginning Balance, Shares at Mar. 31, 2020			15,061
Stock-based compensation expense	3,076				3,076
Net income (loss)	(5,603)						(5,603)
Issuance of common stock upon follow-on public offering net of underwriting discounts and commissions and other offering costs		45,789				45,789
Issuance of common stock upon follow-on public offering net of underwriting discounts and commissions and other offerings costs, Shares				1,525
Issuance of shares upon vesting of restricted stock units, net of tax withholdings	(1,707)				(1,707)
Issuance of shares upon vesting of restricted stock units, net of tax withholdings, Shares			130
Ending Balance at Jun. 30, 2020	99,569		$ 2		164,287		(64,720)
Ending Balance, Shares at Jun. 30, 2020			16,716
Beginning Balance at Dec. 31, 2020	$ 109,880		$ 2		173,274		(63,396)
Beginning Balance, Shares at Dec. 31, 2020	17,150		17,150
Stock-based compensation expense	$ 14,000				14,000
Net income (loss)	(1,542)						(1,542)
Issuance of common stock upon follow-on public offering net of underwriting discounts and commissions and other offering costs		$ 181,588				$ 181,588
Issuance of common stock upon follow-on public offering net of underwriting discounts and commissions and other offerings costs, Shares				1,500
Issuance of shares upon vesting of restricted stock units, net of tax withholdings, Shares			411
Ending Balance at Jun. 30, 2021	$ 303,926		$ 2		368,862		(64,938)
Ending Balance, Shares at Jun. 30, 2021	19,061		19,061
Beginning Balance at Mar. 31, 2021	$ 295,269		$ 2		362,228		(66,961)
Beginning Balance, Shares at Mar. 31, 2021			18,840
Stock-based compensation expense	6,634				6,634
Net income (loss)	2,023						2,023
Issuance of shares upon vesting of restricted stock units, net of tax withholdings, Shares			221
Ending Balance at Jun. 30, 2021	$ 303,926		$ 2		$ 368,862		$ (64,938)
Ending Balance, Shares at Jun. 30, 2021	19,061		19,061