Financial instruments and fair value measurements - Assets measured at fair value (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Financial instruments and fair value measurements
Cash equivalents	$ 83,187	$ 77,736
Debt securities	247,953	283,078
Total assets	331,140	360,814
U.S. Treasury
Financial instruments and fair value measurements
Debt securities	65,197	86,475
Corporate bonds
Financial instruments and fair value measurements
Debt securities	182,756	196,603
Level 1
Financial instruments and fair value measurements
Cash equivalents	83,187	77,736
Total assets	148,384	164,211
Level 1 | U.S. Treasury
Financial instruments and fair value measurements
Debt securities	65,197	86,475
Level 2
Financial instruments and fair value measurements
Total assets	182,756	196,603
Level 2 | Corporate bonds
Financial instruments and fair value measurements
Debt securities	$ 182,756	$ 196,603