Revenue and Related Matters - Schedule of Timing of Revenue Recognition Liabilities per Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,511,041	$ 1,534,130
Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	1,382,486	1,356,740
Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	128,555	177,390
Insights
Disaggregation of Revenue [Line Items]
Total revenues	1,294,195	1,255,569
Insights | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	1,292,253	1,252,188
Insights | Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	1,942	3,381
Conferences
Disaggregation of Revenue [Line Items]
Total revenues	78,325	72,597
Conferences | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Conferences | Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	78,325	72,597
Consulting
Disaggregation of Revenue [Line Items]
Total revenues	119,129	139,706
Consulting | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	90,159	104,152
Consulting | Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	28,970	35,554
Other
Disaggregation of Revenue [Line Items]
Total revenues	19,392	66,258
Other | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	74	400
Other | Transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues	$ 19,318	$ 65,858