Fair Value Measurements and Fair Value of Financial Instruments - Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total assets measured at fair value	$ 493,260	$ 431,863
Fair Value, Recurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Money market funds	232,813	333,585
U.S. Treasury securities	260,447	98,278
Total assets measured at fair value	493,260	431,863
Fair Value, Recurring | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Money market funds	232,813	333,585
U.S. Treasury securities	0	0
Total assets measured at fair value	232,813	333,585
Fair Value, Recurring | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Money market funds	0	0
U.S. Treasury securities	260,447	98,278
Total assets measured at fair value	260,447	98,278
Fair Value, Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Money market funds	0	0
U.S. Treasury securities	0	0
Total assets measured at fair value	$ 0	$ 0