Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Note Receivable [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2019	$ 66,000	$ 60	$ 495,624	$ (16)	$ 318	$ (429,986)
Beginning Balance, shares at Dec. 31, 2019		60,234,784
Net (loss) income	(1,420)	$ 0	0	0	0	(1,420)
Unrealized [gain/loss] on investments	170	0	0	0	170	0
Issuance of common stock upon follow-on offering, net of issuance costs	325,654	$ 6	325,648	0	0	0
Issuance of common stock upon follow-on offering, net of issuance costs, shares		5,980,000
Issuance of common stock under equity incentive plans	24,493	$ 3	24,490	0	0	0
Issuance of common stock under equity incentive plans, shares		2,681,075
Repurchased shares upon vesting of restricted stock units for tax withholdings	(3,709)	$ 0	(3,709)	0	0	0
Repurchased shares upon vesting of restricted stock units for tax withholdings, shares		(92,459)
Employee stock-based compensation	9,450	$ 0	9,450	0	0	0
Compensation expense related to options granted to consultants	503	0	503	0	0	0
Ending Balance at Jun. 30, 2020	421,141	$ 69	852,006	(16)	488	(431,406)
Ending Balance, shares at Jun. 30, 2020		68,803,400
Beginning Balance at Mar. 31, 2020	60,161	$ 62	511,571	(16)	217	(451,673)
Beginning Balance, shares at Mar. 31, 2020		61,792,661
Net (loss) income	20,267	$ 0	0	0	0	20,267
Unrealized [gain/loss] on investments	271	0	0	0	271	0
Issuance of common stock upon follow-on offering, net of issuance costs	325,654	$ 6	325,648	0	0	0
Issuance of common stock upon follow-on offering, net of issuance costs, shares		5,980,000
Issuance of common stock under equity incentive plans	9,694	$ 1	9,693	0	0	0
Issuance of common stock under equity incentive plans, shares		1,035,206
Repurchased shares upon vesting of restricted stock units for tax withholdings	(229)	$ 0	(229)	0	0	0
Repurchased shares upon vesting of restricted stock units for tax withholdings, shares		(4,467)
Employee stock-based compensation	5,076	$ 0	5,076	0	0	0
Compensation expense related to options granted to consultants	247	0	247	0	0	0
Ending Balance at Jun. 30, 2020	421,141	$ 69	852,006	(16)	488	(431,406)
Ending Balance, shares at Jun. 30, 2020		68,803,400
Beginning Balance at Dec. 31, 2020	$ 385,613	$ 69	870,788	(16)	114	(485,342)
Beginning Balance, shares at Dec. 31, 2020	69,452,466	69,452,466
Net (loss) income	$ (68,920)	$ 0	0	0	0	(68,920)
Unrealized [gain/loss] on investments	(195)	0	0	0	(195)	0
Issuance of common stock upon follow-on offering, net of issuance costs	3,262	$ 1	3,261	0	0	0
Issuance of common stock upon follow-on offering, net of issuance costs, shares		519,852
Repurchased shares upon vesting of restricted stock units for tax withholdings	(5,273)	$ 0	(5,273)	0	0	0
Repurchased shares upon vesting of restricted stock units for tax withholdings, shares		(86,343)
Employee stock-based compensation	15,294	$ 0	15,294	0	0	0
Compensation expense related to options granted to consultants	489	0	489	0	0	0
Ending Balance at Jun. 30, 2021	$ 330,270	$ 70	884,559	(16)	(81)	(554,262)
Ending Balance, shares at Jun. 30, 2021	69,885,975	69,885,975
Beginning Balance at Mar. 31, 2021	$ 361,004	$ 70	876,017	(16)	(14)	(515,053)
Beginning Balance, shares at Mar. 31, 2021		69,742,493
Net (loss) income	(39,209)	$ 0	0	0	0	(39,209)
Unrealized [gain/loss] on investments	(67)	0	0	0	(67)	0
Issuance of common stock upon follow-on offering, net of issuance costs	0	$ 0	0	0	0	0
Issuance of common stock upon follow-on offering, net of issuance costs, shares		0
Issuance of common stock under equity incentive plans	1,099	$ 0	1,099	0	0	0
Issuance of common stock under equity incentive plans, shares		148,865
Repurchased shares upon vesting of restricted stock units for tax withholdings	(260)	$ 0	(260)	0	0	0
Repurchased shares upon vesting of restricted stock units for tax withholdings, shares		(5,383)
Employee stock-based compensation	7,454	$ 0	7,454	0	0	0
Compensation expense related to options granted to consultants	249	0	249	0	0	0
Ending Balance at Jun. 30, 2021	$ 330,270	$ 70	$ 884,559	$ (16)	$ (81)	$ (554,262)
Ending Balance, shares at Jun. 30, 2021	69,885,975	69,885,975