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Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Feb. 29, 2024	Aug. 31, 2025	Aug. 31, 2024	Nov. 30, 2024
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 1,847,856	$ 1,827,938	$ 1,847,856
Currency translation and other adjustments		16,255	4,870
Measurement period adjustments		1,802	(28,346)
Goodwill relating to acquisitions by Tessellis			8,578
Write-off related to disposals		(5,563)
Goodwill, ending balance		1,840,432	1,832,958
Goodwill		1,840,400		$ 1,827,900
OpNet
Goodwill [Roll Forward]
Goodwill, beginning balance	127,100		127,100
Measurement period adjustments	27,000
Investment Banking and Capital Markets
Goodwill [Roll Forward]
Goodwill, beginning balance	1,532,172	1,533,013	1,532,172
Currency translation and other adjustments		4,866	3,335
Measurement period adjustments		0	0
Goodwill relating to acquisitions by Tessellis			0
Write-off related to disposals		0
Goodwill, ending balance		1,537,879	1,535,507
Asset Management
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 315,684	294,925	315,684
Currency translation and other adjustments		11,389	1,535
Measurement period adjustments		1,802	(28,346)
Goodwill relating to acquisitions by Tessellis			8,578
Write-off related to disposals		(5,563)
Goodwill, ending balance		302,553	$ 297,451
Goodwill		143,000		143,000
Investment banking
Goodwill [Roll Forward]
Goodwill		702,900		700,700
Equities and wealth management
Goodwill [Roll Forward]
Goodwill		256,200		255,400
Fixed income
Goodwill [Roll Forward]
Goodwill		578,700		576,900
Other investments
Goodwill [Roll Forward]
Goodwill		$ 159,600		$ 151,900