Fair value measurement - Financial assets measured at fair value (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2026	Dec. 31, 2025
Debt Securities, Available-for-Sale [Line Items]
Fair Value		$ 1,300
Maximum
Debt Securities, Available-for-Sale [Line Items]
Contractual maturity term	7 months
Recurring
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 460,894	652,112
Unrealized Loss	(467)
Fair Value	460,427	652,112
Recurring | Level 1 | Money market funds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	211,687	652,112
Fair Value	211,687	$ 652,112
Recurring | Level 2 | Marketable securities (U.S. treasury securities)
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	249,207
Unrealized Loss	(467)
Fair Value	$ 248,740