CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020		45,804
Beginning balance at Dec. 31, 2020	$ 134,260	$ 510,061	$ 14	$ (375,815)
Increase (Decrease) in Shareholders' Equity
Net loss	(3,289)			(3,289)
Stock-based compensation expense	7,019	$ 7,019
Stock option exercises (in shares)		359
Stock option exercises	3,532	$ 3,532
Shares issued under the Employee Stock Purchase Plan (in shares)		14
Shares issued under the Employee Stock Purchase Plan	249	$ 249
Issuance of stock for restricted stock unit vesting (in shares)		76
Restricted stock withheld for employee tax remittance (in shares)		(28)
Restricted stock withheld for employee tax remittance	(1,501)	$ (1,501)
Unrealized loss on investments	(61)		(61)
Ending balance (in shares) at Mar. 31, 2021		46,225
Ending balance at Mar. 31, 2021	140,209	$ 519,360	(47)	(379,104)
Beginning balance (in shares) at Dec. 31, 2020		45,804
Beginning balance at Dec. 31, 2020	134,260	$ 510,061	14	(375,815)
Increase (Decrease) in Shareholders' Equity
Net loss	(12,006)
Unrealized loss on investments	(37)
Ending balance (in shares) at Sep. 30, 2021		46,767
Ending balance at Sep. 30, 2021	156,780	$ 544,624	(23)	(387,821)
Beginning balance (in shares) at Mar. 31, 2021		46,225
Beginning balance at Mar. 31, 2021	140,209	$ 519,360	(47)	(379,104)
Increase (Decrease) in Shareholders' Equity
Net loss	(3,786)			(3,786)
Stock-based compensation expense	10,866	$ 10,866
Stock option exercises (in shares)		330
Stock option exercises	3,531	$ 3,531
Shares issued under the Employee Stock Purchase Plan (in shares)		13
Shares issued under the Employee Stock Purchase Plan	309	$ 309
Issuance of stock for restricted stock unit vesting (in shares)		12
Restricted stock withheld for employee tax remittance (in shares)		(1)
Restricted stock withheld for employee tax remittance	(61)	$ (61)
Unrealized loss on investments	24		24
Ending balance (in shares) at Jun. 30, 2021		46,579
Ending balance at Jun. 30, 2021	151,092	$ 534,005	(23)	(382,890)
Increase (Decrease) in Shareholders' Equity
Net loss	(4,931)			(4,931)
Stock-based compensation expense	8,596	$ 8,596
Stock option exercises (in shares)		176
Stock option exercises	1,676	$ 1,676
Shares issued under the Employee Stock Purchase Plan (in shares)		9
Shares issued under the Employee Stock Purchase Plan	404	$ 404
Issuance of stock for restricted stock unit vesting (in shares)		4
Restricted stock withheld for employee tax remittance (in shares)		(1)
Restricted stock withheld for employee tax remittance	(57)	$ (57)
Unrealized loss on investments	0
Ending balance (in shares) at Sep. 30, 2021		46,767
Ending balance at Sep. 30, 2021	156,780	$ 544,624	(23)	(387,821)
Beginning balance (in shares) at Dec. 31, 2021		46,880
Beginning balance at Dec. 31, 2021	170,462	$ 553,902	(154)	(383,286)
Increase (Decrease) in Shareholders' Equity
Net loss	(7,091)			(7,091)
Stock-based compensation expense	9,531	$ 9,531
Stock option exercises (in shares)		125
Stock option exercises	1,155	$ 1,155
Shares issued under the Employee Stock Purchase Plan (in shares)		9
Shares issued under the Employee Stock Purchase Plan	310	$ 310
Issuance of stock for restricted stock unit vesting (in shares)		108
Restricted stock withheld for employee tax remittance (in shares)		(41)
Restricted stock withheld for employee tax remittance	(1,423)	$ (1,423)
Unrealized loss on investments	(459)		(459)
Ending balance (in shares) at Mar. 31, 2022		47,081
Ending balance at Mar. 31, 2022	172,485	$ 563,475	(613)	(390,377)
Beginning balance (in shares) at Dec. 31, 2021		46,880
Beginning balance at Dec. 31, 2021	170,462	$ 553,902	(154)	(383,286)
Increase (Decrease) in Shareholders' Equity
Net loss	(22,631)
Unrealized loss on investments	(992)
Ending balance (in shares) at Sep. 30, 2022		47,201
Ending balance at Sep. 30, 2022	177,837	$ 584,900	(1,146)	(405,917)
Beginning balance (in shares) at Mar. 31, 2022		47,081
Beginning balance at Mar. 31, 2022	172,485	$ 563,475	(613)	(390,377)
Increase (Decrease) in Shareholders' Equity
Net loss	(8,963)			(8,963)
Stock-based compensation expense	10,808	$ 10,808
Stock option exercises (in shares)		32
Stock option exercises	428	$ 428
Shares issued under the Employee Stock Purchase Plan (in shares)		10
Shares issued under the Employee Stock Purchase Plan	318	$ 318
Issuance of stock for restricted stock unit vesting (in shares)		19
Restricted stock withheld for employee tax remittance (in shares)		(1)
Restricted stock withheld for employee tax remittance	(18)	$ (18)
Unrealized loss on investments	(242)		(242)
Ending balance (in shares) at Jun. 30, 2022		47,141
Ending balance at Jun. 30, 2022	174,816	$ 575,011	(855)	(399,340)
Increase (Decrease) in Shareholders' Equity
Net loss	(6,577)			(6,577)
Stock-based compensation expense	9,104	$ 9,104
Stock option exercises (in shares)		41
Stock option exercises	498	$ 498
Shares issued under the Employee Stock Purchase Plan (in shares)		15
Shares issued under the Employee Stock Purchase Plan	331	$ 331
Issuance of stock for restricted stock unit vesting (in shares)		6
Restricted stock withheld for employee tax remittance (in shares)		(2)
Restricted stock withheld for employee tax remittance	(44)	$ (44)
Unrealized loss on investments	(291)		(291)
Ending balance (in shares) at Sep. 30, 2022		47,201
Ending balance at Sep. 30, 2022	$ 177,837	$ 584,900	$ (1,146)	$ (405,917)