Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues:
Total revenues	$ 1,484,306	$ 1,408,784	$ 4,552,292	$ 4,320,838
Costs and expenses:
Cost of services and product development	475,342	450,841	1,448,097	1,373,398
Selling, general and administrative	711,729	660,527	2,113,633	1,997,785
Depreciation	29,082	24,547	82,993	72,155
Amortization of intangibles	22,170	23,989	68,100	69,625
Acquisition and integration charges	159	4,463	977	7,804
Gain from sale of divested operation	0	0	0	(135,410)
Total costs and expenses	1,238,482	1,164,367	3,713,800	3,385,357
Operating income	245,824	244,417	838,492	935,481
Interest expense, net	(17,961)	(21,820)	(57,170)	(73,769)
Gain on event cancellation insurance claims	300,000	0	300,000	3,077
Other (expense) income, net	(991)	1,877	4,404	5,086
Income before income taxes	526,872	224,474	1,085,726	869,875
Provision for income taxes	111,823	44,465	230,584	196,040
Net income	$ 415,049	$ 180,009	$ 855,142	$ 673,835
Net income per share:
Basic (in dollars per share)	$ 5.36	$ 2.28	$ 10.98	$ 8.51
Diluted (in dollars per share)	$ 5.32	$ 2.26	$ 10.90	$ 8.44
Weighted average shares outstanding:
Basic (in shares)	77,484	78,923	77,880	79,220
Diluted (in shares)	77,968	79,520	78,444	79,862
Research
Revenues:
Total revenues	$ 1,280,908	$ 1,218,739	$ 3,815,072	$ 3,643,815
Conferences
Revenues:
Total revenues	75,776	57,200	331,929	290,739
Consulting
Revenues:
Total revenues	$ 127,622	$ 132,845	$ 405,291	$ 386,284