Deferred Revenue from Membership Upgrade Sales and Deferred Commission Expense (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Movement in Deferred Revenue [Roll Forward]
Deferred revenue - upfront payments from membership upgrade sales, beginning	$ 197,743
Revenue recognized from membership upgrade sales upfront payments	(10,863)	$ (9,543)
Net increase in deferred revenue - upfront payments from membership grade sales	29,140	28,080
Deferred revenue - upfront payments from membership upgrade sales, ending (a)	216,021
Deferred Commissions Expense
Movement in Deferred Sales Inducements [Roll Forward]
Deferred commission expense, beginning	50,441	47,349
Deferred commission expense	5,850	5,594
Commission expense recognized	(3,122)	(2,850)
Net increase in deferred commission expense	2,728	2,744
Deferred commission expense, ending	53,169	50,093
Membership Subscription
Movement in Deferred Revenue [Roll Forward]
Deferred revenue - upfront payments from membership upgrade sales, beginning	185,660	163,957
Membership upgrade sales, gross	28,041	27,771
Revenue recognized from membership upgrade sales upfront payments	(10,863)	(9,543)
Net increase in deferred revenue - upfront payments from membership grade sales	17,178	18,228
Deferred revenue - upfront payments from membership upgrade sales, ending (a)	$ 202,838	$ 182,185