Fair value measurements - Assets and liabilities measured on a recurring basis - (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	$ 76,127	$ 68,802
Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Total money market funds and marketable securities	358,748	227,663
Level 1 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Total money market funds and marketable securities	213,274	199,708
Level 2 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Total money market funds and marketable securities	145,474	27,955
U.S. Treasury notes | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	22,714	103,044
U.S. Treasury notes | Level 1 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	22,714	103,044
U. S. Government agency securities | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	126,706	31,075
U. S. Government agency securities | Level 1 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	126,706	31,075
Corporate bonds | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	113,661	23,970
Corporate bonds | Level 2 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	113,661	23,970
Commercial paper | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	26,364	3,985
Commercial paper | Level 2 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	26,364	3,985
Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	63,854	65,589
Money market funds | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	63,854	65,589
Money market funds | Level 1 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	63,854	$ 65,589
Certificates of deposits | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	5,449
Certificates of deposits | Level 2 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	$ 5,449