Fair Value Measurements - Debt Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 425,397	$ 561,100
Gross Unrealized Gains	120	0
Gross Unrealized Losses	0	0
Estimated Fair Value	425,517	561,100
U.S. Government
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	425,397	561,100
Gross Unrealized Gains	120	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 425,517	$ 561,100