Segment Information - Reconciliation of Segment Gross Contribution to Net Income (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended						9 Months Ended
	May 31, 2021	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment gross contribution		$ 253,418			$ 230,221			$ 767,787	$ 730,347
Costs and expenses:
Cost of services and product development - unallocated		416,837			359,237			1,218,405	1,044,506
Selling, general and administrative		613,031			512,573			1,835,846	1,488,324
Acquisition and integration charges		1,331			1,771			5,827	3,713
Operating income		253,418			230,221			767,787	730,347
Interest expense and other, net		(21,356)			(31,388)			(44,715)	(73,119)
Gain on event cancellation insurance claims	$ 135,500	0			0			0	135,545
Less: Provision for income taxes		58,517			49,968			172,087	208,572
Net income		173,545	$ 204,925	$ 172,515	148,865	$ 271,236	$ 164,100	550,985	584,201
Reportable segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment gross contribution		925,969			811,519			2,791,198	2,416,388
Costs and expenses:
Operating income		925,969			811,519			$ 2,791,198	2,416,388
Reportable segments | Maximum
Costs and expenses:
Percent of target bonus allocated to segments								100.00%
Corporate and other expenses
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment gross contribution		(672,551)			(581,298)			$ (2,023,411)	(1,686,041)
Costs and expenses:
Cost of services and product development - unallocated		10,938			14,474			38,474	33,255
Selling, general and administrative		613,031			512,573			1,835,846	1,488,324
Depreciation and amortization		47,251			52,480			143,264	160,749
Acquisition and integration charges		1,331			1,771			5,827	3,713
Operating income		$ (672,551)			$ (581,298)			$ (2,023,411)	$ (1,686,041)