Deferred Revenue of Membership Upgrade Sales and Deferred Commission Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Movement in Deferred Revenue
Deferred revenue - upfront payments from membership upgrade sales as of December 31,	$ 197,743
Revenue recognized from membership upgrade sales upfront payments	(14,719)	$ (12,958)	$ (11,191)
Net increase in deferred revenue - upfront payments from membership grade sales	35,313	33,946	36,935
Deferred revenue - upfront payments from membership upgrade sales as of December 31,	218,337	197,743
Movement in Deferred Costs
Deferred commission expense as of December 31,	50,441	47,349
Deferred commission expense	7,411	7,193
Commission expense recognized	(4,211)	(4,101)
Net increase in deferred commission expense	3,200	3,092
Deferred commission expense as of December 31,	53,641	50,441	47,349
Membership Subscriptions
Movement in Deferred Revenue
Deferred revenue - upfront payments from membership upgrade sales as of December 31,	185,660	163,957
Membership upgrade sales	35,684	34,661
Revenue recognized from membership upgrade sales upfront payments	(14,719)	(12,958)
Net increase in deferred revenue - upfront payments from membership grade sales	20,965	21,703
Deferred revenue - upfront payments from membership upgrade sales as of December 31,	$ 206,625	$ 185,660	$ 163,957