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Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2017	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Oct. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period	6 months
Options outstanding (in shares)		10,500,755		10,500,755		8,373,921
Weighted-average exercise price of stock options outstanding (in dollars per share)		$ 18.66		$ 18.66		$ 21.47
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 5,300	$ 6,070	$ 10,574	$ 11,356
2016 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)	800,000
Payroll deduction percentage	10.00%
Purchase price of common stock percent of the fair market value	85.00%
Common stock purchased (in shares)				65,125
2003 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)		105,282		105,282
Stock Incentive Plan 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation, number of shares authorized (in shares)		15,816,949		15,816,949
Options outstanding (in shares)		10,395,473		10,395,473
Potential annual increase in shares reserved for future issuance (in shares)							1,960,168
Potential annual increase in shares reserved for future issuance as percentage of outstanding share				4.00%
Research and Development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 2,658	3,058	$ 5,050	5,785
General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 2,642	$ 3,012	$ 5,524	$ 5,571

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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