Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring basis - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Quoted prices in active markets for identical assets (Level 1) | Investments in money market funds*
Fair Value Measurements
Investments	$ 143,165	$ 251,488
Quoted prices in active markets for identical assets (Level 1) | Investments in U.S. Treasury securities
Fair Value Measurements
Investments	47,818	18,185
Quoted prices in active markets for identical assets (Level 1) | Investments in corporate debt securities
Fair Value Measurements
Investments	0	0
Quoted prices in active markets for identical assets (Level 1) | Investments in asset-backed securities
Fair Value Measurements
Investments	0	0
Quoted prices in active markets for identical assets (Level 1) | Investments in supranational securities
Fair Value Measurements
Investments	0	0
Significant other observable inputs (Level 2) | Investments in money market funds*
Fair Value Measurements
Investments	0	0
Significant other observable inputs (Level 2) | Investments in U.S. Treasury securities
Fair Value Measurements
Investments	0	0
Significant other observable inputs (Level 2) | Investments in corporate debt securities
Fair Value Measurements
Investments	100,211	82,081
Significant other observable inputs (Level 2) | Investments in asset-backed securities
Fair Value Measurements
Investments	14,436	15,995
Significant other observable inputs (Level 2) | Investments in supranational securities
Fair Value Measurements
Investments	4,970	4,041
Significant unobservable inputs (Level 3) | Investments in money market funds*
Fair Value Measurements
Investments	0	0
Significant unobservable inputs (Level 3) | Investments in U.S. Treasury securities
Fair Value Measurements
Investments	0	0
Significant unobservable inputs (Level 3) | Investments in corporate debt securities
Fair Value Measurements
Investments	0	0
Significant unobservable inputs (Level 3) | Investments in asset-backed securities
Fair Value Measurements
Investments	0	0
Significant unobservable inputs (Level 3) | Investments in supranational securities
Fair Value Measurements
Investments	$ 0	$ 0