Segment Information - Reconciliation of Segment Gross Contribution to Net Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment gross contribution	$ 1,236,894	$ 1,100,106	$ 915,751
Costs and expenses:
Cost of services and product development	1,903,240	1,693,771	1,444,093
Selling, general and administrative	2,701,542	2,480,944	2,155,658
Acquisition and integration charges	9,587	9,079	6,055
Gain from sale of divested operation	(135,410)	0	0
Operating income	1,236,894	1,100,106	915,751
Interest expense and other, net	(92,842)	(72,911)	(98,191)
Gain on event cancellation insurance claims	3,077	0	152,310
Provision for income taxes	264,663	219,396	176,310
Net income	$ 882,466	807,799	793,560
Maximum
Costs and expenses:
Percent of target bonus charges allocated to segments	100.00%
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment gross contribution	$ 4,035,383	3,815,134	3,329,516
Costs and expenses:
Operating income	4,035,383	3,815,134	3,329,516
Corporate and Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment gross contribution	(2,798,489)	(2,715,028)	(2,413,765)
Costs and expenses:
Cost of services and product development	31,667	33,059	39,647
Selling, general and administrative	2,701,542	2,480,944	2,155,658
Depreciation and amortization	191,103	191,946	212,405
Acquisition and integration charges	9,587	9,079	6,055
Gain from sale of divested operation	(135,410)	0	0
Operating income	$ (2,798,489)	$ (2,715,028)	$ (2,413,765)