Fair Value Measurements - Level of the fair value hierarchy (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Fair Value Measurements
Total fair value of financial assets	$ 778,534	$ 875,336
LEVEL 1
Fair Value Measurements
Total fair value of financial assets	392,799	424,343
LEVEL 2
Fair Value Measurements
Total fair value of financial assets	385,735	450,993
Recurring \| Money market funds
Fair Value Measurements
Total fair value of financial assets	139,062	161,328
Recurring \| U.S. government bonds
Fair Value Measurements
Total fair value of financial assets	253,737	263,015
Recurring \| U.S. government agency bonds
Fair Value Measurements
Total fair value of financial assets	37,580	46,957
Recurring \| Corporate debt securities
Fair Value Measurements
Total fair value of financial assets	348,155	404,036
Recurring \| LEVEL 1 \| Money market funds
Fair Value Measurements
Total fair value of financial assets	139,062	161,328
Recurring \| LEVEL 1 \| U.S. government bonds
Fair Value Measurements
Total fair value of financial assets	253,737	263,015
Recurring \| LEVEL 2 \| U.S. government agency bonds
Fair Value Measurements
Total fair value of financial assets	37,580	46,957
Recurring \| LEVEL 2 \| Corporate debt securities
Fair Value Measurements
Total fair value of financial assets	$ 348,155	$ 404,036