CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Shares	Additional paid in capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Balance (in shares) at Dec. 31, 2021		141,600
Balance at Dec. 31, 2021	$ 479,091	$ 1,177,051	$ 59,014	$ (852)	$ (756,122)
Increase (Decrease) in Stockholders' Equity
Shares issued on exercise of stock options and vesting of performance awards and restricted stock units (in shares)		383
Shares issued on exercise of stock options and vesting of restricted stock units	522	$ 5,064	(4,542)
Issuance of common shares in conjunction with ESPP program (in shares)		127
Issuance of common shares in conjunction with ESPP program	1,223	$ 1,905	(682)
Share-based compensation	25,398		25,398
Unrealized gain (loss) on available-for-sale securities, net	(675)			(675)
Net loss	(82,134)				(82,134)
Balance (in shares) at Sep. 30, 2022		142,110
Balance at Sep. 30, 2022	423,425	$ 1,184,020	79,188	(1,527)	(838,256)
Balance (in shares) at Jun. 30, 2022		141,892
Balance at Jun. 30, 2022	423,768	$ 1,180,884	74,004	(1,853)	(829,267)
Increase (Decrease) in Stockholders' Equity
Shares issued on exercise of stock options and vesting of performance awards and restricted stock units (in shares)		218
Shares issued on exercise of stock options and vesting of restricted stock units	0	$ 3,136	(3,136)
Share-based compensation	8,320		8,320
Unrealized gain (loss) on available-for-sale securities, net	326			326
Net loss	(8,989)				(8,989)
Balance (in shares) at Sep. 30, 2022		142,110
Balance at Sep. 30, 2022	$ 423,425	$ 1,184,020	79,188	(1,527)	(838,256)
Balance (in shares) at Dec. 31, 2022	142,268	142,268
Balance at Dec. 31, 2022	$ 405,435	$ 1,185,309	85,489	(1,061)	(864,302)
Increase (Decrease) in Stockholders' Equity
Shares issued on exercise of stock options and vesting of performance awards and restricted stock units (in shares)	558	1,127
Shares issued on exercise of stock options and vesting of restricted stock units	$ 3,024	$ 11,141	(8,117)
Issuance of common shares in conjunction with ESPP program (in shares)		210
Issuance of common shares in conjunction with ESPP program	906	$ 2,110	(1,204)
Share-based compensation	33,543		33,543
Unrealized gain (loss) on available-for-sale securities, net	114			114
Net loss	$ (51,145)				(51,145)
Balance (in shares) at Sep. 30, 2023	143,605	143,605
Balance at Sep. 30, 2023	$ 391,877	$ 1,198,560	109,711	(947)	(915,447)
Balance (in shares) at Jun. 30, 2023		143,369
Balance at Jun. 30, 2023	392,292	$ 1,196,480	98,832	(1,020)	(902,000)
Increase (Decrease) in Stockholders' Equity
Shares issued on exercise of stock options and vesting of performance awards and restricted stock units (in shares)		236
Shares issued on exercise of stock options and vesting of restricted stock units	1,151	$ 2,080	(929)
Share-based compensation	11,808		11,808
Unrealized gain (loss) on available-for-sale securities, net	73			73
Net loss	$ (13,447)				(13,447)
Balance (in shares) at Sep. 30, 2023	143,605	143,605
Balance at Sep. 30, 2023	$ 391,877	$ 1,198,560	$ 109,711	$ (947)	$ (915,447)