Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)
Common stock at beginning of period (in shares) at Dec. 31, 2017			23,377,315
Common stock balance at beginning of period at Dec. 31, 2017	$ 79,341	$ 1,354	$ 23	$ 236,184	$ (156,801)	$ 1,354	$ (65)
Increase (Decrease) in Stockholders' and Temporary Equity [Roll Forward]
Issuance of common stock in connection with employee equity incentive plans, net (in shares)	798,424		990,758
Issuance of common stock in connection with employee equity incentive plans	$ 9,319			9,319
Tax withholding upon vesting of restricted stock awards	(3,877)			(3,877)
Stock-based compensation expense	16,329			16,329
Net loss	(50,378)				(50,378)
Net change in unrealized gains (losses) on available-for-sale securities	49						49
Common stock at end of period (in shares) at Dec. 31, 2018			24,368,073
Common stock balance at end of period at Dec. 31, 2018	$ 52,137		$ 23	257,955	(205,825)		(16)
Increase (Decrease) in Stockholders' and Temporary Equity [Roll Forward]
Issuance of common stock in connection with employee equity incentive plans, net (in shares)	540,307		734,453
Issuance of common stock in connection with employee equity incentive plans	$ 9,495			9,495
Warrants exercised (in shares)			4,852
Issuance of common stock in connection with follow-on public offering, net of discounts and issuance costs (in shares)			1,575,342
Issuance of common stock in connection with follow-on public offering, net of issuance costs	107,294		$ 2	107,292
Tax withholding upon vesting of restricted stock awards	(5,288)			(5,288)
Stock-based compensation expense	26,241			26,241
Net loss	(54,568)				(54,568)
Net change in unrealized gains (losses) on available-for-sale securities	$ 98						98
Common stock at end of period (in shares) at Dec. 31, 2019	26,682,720		26,682,720
Common stock balance at end of period at Dec. 31, 2019	$ 135,409	$ (461)	$ 25	395,695	(260,393)	$ (461)	82
Increase (Decrease) in Stockholders' and Temporary Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Issuance of common stock in connection with employee equity incentive plans, net (in shares)	868,614		1,079,488
Issuance of common stock in connection with employee equity incentive plans	$ 20,244			20,244
Issuance of common stock in connection with follow-on public offering, net of discounts and issuance costs (in shares)			1,257,142
Issuance of common stock in connection with follow-on public offering, net of issuance costs	206,025		$ 2	206,023
Tax withholding upon vesting of restricted stock awards	(10,009)			(10,009)
Stock-based compensation expense	34,305			34,305
Net loss	(43,830)				(43,830)
Net change in unrealized gains (losses) on available-for-sale securities	$ (71)						(71)
Common stock at end of period (in shares) at Dec. 31, 2020	29,019,350		29,019,350
Common stock balance at end of period at Dec. 31, 2020	$ 341,612		$ 27	$ 646,258	$ (304,684)		$ 11