Goodwill and Intangible Assets - Changes to the Carrying Amount of Goodwill by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Goodwill [Roll Forward]
Beginning balance			$ 2,930,205
Impairment loss	$ (150,000)	$ 0	(150,000)	$ 0
Foreign currency translation impact			9,718
Ending balance	2,789,923		2,789,923
Accumulated impairment losses	(150,000)		(150,000)
Insights
Goodwill [Roll Forward]
Beginning balance			2,453,880
Impairment loss			0
Foreign currency translation impact			6,273
Ending balance	2,460,153		2,460,153
Accumulated impairment losses	0		0
Conferences
Goodwill [Roll Forward]
Beginning balance			183,920
Impairment loss			0
Foreign currency translation impact			135
Ending balance	184,055		184,055
Accumulated impairment losses	0		0
Consulting
Goodwill [Roll Forward]
Beginning balance			95,304
Impairment loss			0
Foreign currency translation impact			1,198
Ending balance	96,502		96,502
Accumulated impairment losses	0		0
Other
Goodwill [Roll Forward]
Beginning balance			197,101
Impairment loss			(150,000)
Foreign currency translation impact			2,112
Ending balance	49,213		49,213
Accumulated impairment losses	$ (150,000)		$ (150,000)