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)		1,441
Exercise of stock options	10,919	$ 15	10,904
Vesting of restricted stock units (in shares)		1,533
Vesting of restricted stock units	0	$ 15	(15)
Issuance of common stock under employee stock purchase plan (in shares)		671
Issuance of common stock under employee stock purchase plan	13,736	$ 7	13,729
Stock-based compensation	58,394		58,394
Other comprehensive income loss	(25)			(25)
Net loss	(35,632)				(35,632)
Ending Balance (in shares) at Sep. 30, 2021		107,360
Ending Balance at Sep. 30, 2021	198,057	$ 1,074	840,482	(15)	(643,484)
Beginning Balance (in shares) at Jun. 30, 2021		106,510
Beginning Balance at Jun. 30, 2021	185,455	$ 1,065	811,644	(16)	(627,238)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Exercise of stock options (in shares)		229
Exercise of stock options	2,215	$ 3	2,212
Vesting of restricted stock units (in shares)		349
Vesting of restricted stock units	0	$ 3	(3)
Issuance of common stock under employee stock purchase plan (in shares)		272
Issuance of common stock under employee stock purchase plan	5,690	$ 3	5,687
Stock-based compensation	20,942		20,942
Other comprehensive income loss	1			1
Net loss	(16,246)				(16,246)
Ending Balance (in shares) at Sep. 30, 2021		107,360
Ending Balance at Sep. 30, 2021	$ 198,057	$ 1,074	840,482	(15)	(643,484)
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)	1,090	1,090
Exercise of stock options	$ 10,655	$ 11	10,644
Vesting of restricted stock units (in shares)		1,939
Vesting of restricted stock units	0	$ 19	(19)
Issuance of common stock under employee stock purchase plan (in shares)		443
Issuance of common stock under employee stock purchase plan	14,791	$ 5	14,786
Stock-based compensation	91,394		91,394
Other comprehensive income loss	(1,563)			(1,563)
Net loss	$ (70,735)				(70,735)
Ending Balance (in shares) at Sep. 30, 2022	112,401	112,401
Ending Balance at Sep. 30, 2022	$ 259,855	$ 1,124	985,864	(1,869)	(725,264)
Beginning Balance (in shares) at Jun. 30, 2022		111,574
Beginning Balance at Jun. 30, 2022	237,525	$ 1,116	944,799	(1,856)	(706,534)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Exercise of stock options (in shares)		158
Exercise of stock options	1,979	$ 2	1,977
Vesting of restricted stock units (in shares)		482
Vesting of restricted stock units	0	$ 4	(4)
Issuance of common stock under employee stock purchase plan (in shares)		187
Issuance of common stock under employee stock purchase plan	5,909	$ 2	5,907
Stock-based compensation	33,185		33,185
Other comprehensive income loss	(13)			(13)
Net loss	$ (18,730)				(18,730)
Ending Balance (in shares) at Sep. 30, 2022	112,401	112,401
Ending Balance at Sep. 30, 2022	$ 259,855	$ 1,124	$ 985,864	$ (1,869)	$ (725,264)