CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning Balance (in shares) at Dec. 31, 2020		103,715
Beginning Balance at Dec. 31, 2020	$ 150,665	$ 1,037	$ 757,470	$ 10	$ (607,852)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Exercise of stock options (in shares)		607
Exercise of stock options	4,015	$ 6	4,009
Vesting of restricted stock units (in shares)		792
Vesting of restricted stock units	0	$ 8	(8)
Issuance of common stock under employee stock purchase plan (in shares)		399
Issuance of common stock under employee stock purchase plan	8,046	$ 4	8,042
Stock-based compensation	16,963		16,963
Other comprehensive loss	(2)			(2)
Net loss	(7,748)				(7,748)
Ending Balance (in shares) at Mar. 31, 2021		105,513
Ending Balance at Mar. 31, 2021	$ 171,939	$ 1,055	786,476	8	(615,600)
Beginning Balance (in shares) at Dec. 31, 2021	108,929	108,929
Beginning Balance at Dec. 31, 2021	$ 215,313	$ 1,089	869,059	(306)	(654,529)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Exercise of stock options (in shares)	293	293
Exercise of stock options	$ 2,587	$ 3	2,584
Vesting of restricted stock units (in shares)		809
Vesting of restricted stock units	0	$ 8	(8)
Issuance of common stock under employee stock purchase plan (in shares)		256
Issuance of common stock under employee stock purchase plan	8,882	$ 3	8,879
Stock-based compensation	25,749		25,749
Other comprehensive loss	(1,057)			(1,057)
Net loss	$ (24,506)				(24,506)
Ending Balance (in shares) at Mar. 31, 2022	110,287	110,287
Ending Balance at Mar. 31, 2022	$ 226,968	$ 1,103	$ 906,263	$ (1,363)	$ (679,035)