Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Public Offering	Common Stock	Common Stock Public Offering	Additional Paid-In Capital	Additional Paid-In Capital Public Offering	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ 192,653		$ 31		$ 370,561		$ 35	$ (177,974)
Beginning balance, Shares at Dec. 31, 2019			31,446,787
Exercise of stock options	1,113		$ 1		1,112
Exercise of stock options, Shares			356,128
Unrealized gain (loss) on available-for- sale securities	68						68
Issuance of common stock under employee stock purchase plan	842				842
Issuance of common stock under employee stock purchase plan, Share			24,691
Stock-based compensation	1,871				1,871
Net income (loss)	(18,775)							(18,775)
Ending balance at Mar. 31, 2020	177,772		$ 32		374,386		103	(196,749)
Ending balance, shares at Mar. 31, 2020			31,827,606
Beginning balance at Dec. 31, 2019	192,653		$ 31		370,561		35	(177,974)
Beginning balance, Shares at Dec. 31, 2019			31,446,787
Net gain reclassified from accumulated other comprehensive income	(21)
Net income (loss)	(49,825)
Ending balance at Sep. 30, 2020	237,047		$ 34		464,812			(227,799)
Ending balance, shares at Sep. 30, 2020			34,236,165
Beginning balance at Mar. 31, 2020	177,772		$ 32		374,386		103	(196,749)
Beginning balance, Shares at Mar. 31, 2020			31,827,606
Exercise of stock options	480				480
Exercise of stock options, Shares			137,178
Unrealized gain (loss) on available-for- sale securities	(82)						(82)
Issuance of common stock in connection with public offering, net of issuance costs		$ 83,382		$ 2		$ 83,380
Issuance of common stock in connection with initial/public offering, Shares				1,955,000
Restricted stock units withheld in net settlement for tax	(616)				(616)
Restricted stock units withheld in net settlement for tax, Shares			(15,456)
Issuance of common stock in connection with vesting of restricted stock, Shares			41,229
Stock-based compensation	2,605				2,605
Net income (loss)	(18,118)							(18,118)
Ending balance at Jun. 30, 2020	245,423		$ 34		460,235		21	(214,867)
Ending balance, shares at Jun. 30, 2020			33,945,557
Exercise of stock options	993				993
Exercise of stock options, Shares			254,523
Issuance of common stock under employee stock purchase plan	953				953
Issuance of common stock under employee stock purchase plan, Share			27,921
Issuance of common stock in connection with public offering, net of issuance costs	(14)				(14)
Restricted stock units withheld in net settlement for tax	(246)				(246)
Restricted stock units withheld in net settlement for tax, Shares			(4,611)
Issuance of common stock in connection with vesting of restricted stock, Shares			12,775
Stock-based compensation	2,891				2,891
Net gain reclassified from accumulated other comprehensive income	(21)						(21)
Net income (loss)	(12,932)							(12,932)
Ending balance at Sep. 30, 2020	237,047		$ 34		464,812			(227,799)
Ending balance, shares at Sep. 30, 2020			34,236,165
Beginning balance at Dec. 31, 2020	225,654		$ 35		469,283		9	(243,673)
Beginning balance, Shares at Dec. 31, 2020			34,684,337
Exercise of stock options	773				773
Exercise of stock options, Shares			159,325
Unrealized gain (loss) on available-for- sale securities	7						7
Issuance of common stock under employee stock purchase plan	1,141				1,141
Issuance of common stock under employee stock purchase plan, Share			20,594
Restricted stock units withheld in net settlement for tax	(5,114)				(5,114)
Restricted stock units withheld in net settlement for tax, Shares			(42,529)
Issuance of common stock in connection with vesting of restricted stock, Shares			107,237
Stock-based compensation	5,394				5,394
Net income (loss)	(23,601)							(23,601)
Ending balance at Mar. 31, 2021	204,254		$ 35		471,477		16	(267,274)
Ending balance, shares at Mar. 31, 2021			34,928,964
Beginning balance at Dec. 31, 2020	$ 225,654		$ 35		469,283		9	(243,673)
Beginning balance, Shares at Dec. 31, 2020			34,684,337
Exercise of stock options, Shares	431,041
Net income (loss)	$ (22,078)
Ending balance at Sep. 30, 2021	220,291		$ 35		486,014		(7)	(265,751)
Ending balance, shares at Sep. 30, 2021			35,294,952
Beginning balance at Mar. 31, 2021	204,254		$ 35		471,477		16	(267,274)
Beginning balance, Shares at Mar. 31, 2021			34,928,964
Exercise of stock options	1,085				1,085
Exercise of stock options, Shares			149,101
Unrealized gain (loss) on available-for- sale securities	(6)						(6)
Restricted stock units withheld in net settlement for tax	(3,223)				(3,223)
Restricted stock units withheld in net settlement for tax, Shares			(20,537)
Issuance of common stock in connection with vesting of restricted stock, Shares			71,761
Stock-based compensation	6,662				6,662
Net income (loss)	(425)							(425)
Ending balance at Jun. 30, 2021	208,347		$ 35		476,001		10	(267,699)
Ending balance, shares at Jun. 30, 2021			35,129,289
Exercise of stock options	691				691
Exercise of stock options, Shares			122,615
Unrealized gain (loss) on available-for- sale securities	(17)						(17)
Issuance of common stock under employee stock purchase plan	1,696				1,696
Issuance of common stock under employee stock purchase plan, Share			16,239
Issuance of common stock in connection with vesting of restricted stock, Shares			26,809
Stock-based compensation	7,626				7,626
Net income (loss)	1,948							1,948
Ending balance at Sep. 30, 2021	$ 220,291		$ 35		$ 486,014		$ (7)	$ (265,751)
Ending balance, shares at Sep. 30, 2021			35,294,952