Collateralized Transactions - Contractual Maturity (Details) - USD ($) $ in Millions	Feb. 28, 2025	Nov. 30, 2024
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	$ 2,501.6	$ 2,540.9
Repurchase Agreements	20,685.4	18,088.9
Obligation to Return Securities Received as Collateral, at Fair Value	287.1	185.6
Total	23,474.1	20,815.4
Overnight and Continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	1,552.0	1,617.8
Repurchase Agreements	2,601.6	2,258.1
Obligation to Return Securities Received as Collateral, at Fair Value	287.1	185.6
Total	4,440.7	4,061.5
Up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	138.4	154.3
Repurchase Agreements	8,388.2	7,055.1
Obligation to Return Securities Received as Collateral, at Fair Value	0.0	0.0
Total	8,526.6	7,209.4
31-90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	383.8	250.4
Repurchase Agreements	5,671.7	4,182.8
Obligation to Return Securities Received as Collateral, at Fair Value	0.0	0.0
Total	6,055.5	4,433.2
Greater than 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Lending Arrangements	427.4	518.4
Repurchase Agreements	4,023.9	4,592.9
Obligation to Return Securities Received as Collateral, at Fair Value	0.0	0.0
Total	$ 4,451.3	$ 5,111.2