Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenues:
Total revenues	$ 1,472,926	$ 1,408,869
Costs and expenses:
Cost of services and product development	459,441	435,139
Selling, general and administrative	689,833	657,090
Depreciation	26,317	23,896
Amortization of intangibles	22,990	22,735
Acquisition and integration charges	460	1,368
Gain from sale of divested operation	0	(139,316)
Total costs and expenses	1,199,041	1,000,912
Operating income	273,885	407,957
Interest expense, net	(19,219)	(27,391)
Gain on event cancellation insurance claims	0	3,077
Other income (expense), net	4,891	(2,366)
Income before income taxes	259,557	381,277
Provision for income taxes	49,012	85,494
Net income	$ 210,545	$ 295,783
Net income per share:
Basic (in dollars per share)	$ 2.69	$ 3.72
Diluted (in dollars per share)	$ 2.67	$ 3.68
Weighted average shares outstanding:
Basic (in shares)	78,339	79,452
Diluted (in shares)	78,964	80,282
Research
Revenues:
Total revenues	$ 1,268,172	$ 1,217,191
Conferences
Revenues:
Total revenues	70,069	64,642
Consulting
Revenues:
Total revenues	$ 134,685	$ 127,036