Collateralized Transactions - Contractual Maturity (Details) - USD ($) $ in Millions	Nov. 30, 2024	Nov. 30, 2023
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	$ 2,540.9	$ 1,840.5
Repurchase Agreements	18,088.9	19,841.2
Obligation to Return Securities Received as Collateral, at Fair Value	185.6	8.8
Total	20,815.4	21,690.5
Overnight and Continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	1,617.8	1,068.6
Repurchase Agreements	2,258.1	10,548.3
Obligation to Return Securities Received as Collateral, at Fair Value	185.6	8.8
Total	4,061.5	11,625.7
Up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	154.3	0.0
Repurchase Agreements	7,055.1	2,442.4
Obligation to Return Securities Received as Collateral, at Fair Value	0.0	0.0
Total	7,209.4	2,442.4
31-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	250.4	244.2
Repurchase Agreements	4,182.8	1,939.9
Obligation to Return Securities Received as Collateral, at Fair Value	0.0	0.0
Total	4,433.2	2,184.1
Greater than 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	518.4	527.7
Repurchase Agreements	4,592.9	4,910.6
Obligation to Return Securities Received as Collateral, at Fair Value	0.0	0.0
Total	$ 5,111.2	$ 5,438.3