Revenue - Deferred revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue
Balance, beginning of the period	$ 174,011	$ 182,540	$ 210,885	$ 154,777
Deferral of revenue	31,544	62,787	65,222	154,216
Recognition of deferred revenue	(41,529)	(43,298)	(112,081)	(106,964)
Balance, end of the period	164,026	$ 202,029	164,026	$ 202,029
Reclassification from deferred revenue to refund liability	$ 4,700		$ 4,700