Variable Interest Entities - Assets and Liabilities of Consolidated VIEs Prior to Consolidation (Details) - USD ($) $ in Millions	Aug. 31, 2019	Nov. 30, 2018
Securitization Vehicles
Variable Interest Entity [Line Items]
Total assets	$ 1,822.1	$ 883.1
Total liabilities	1,822.1	883.1
Secured financing included in inventory and eliminated		1.0
Securitization Vehicles | Cash
Variable Interest Entity [Line Items]
Total assets	0.0	0.0
Securitization Vehicles | Financial instruments owned
Variable Interest Entity [Line Items]
Total assets	0.0	0.0
Securitization Vehicles | Securities purchased under agreement to resell
Variable Interest Entity [Line Items]
Total assets	1,822.1	883.1
Securitization Vehicles | Other secured financings
Variable Interest Entity [Line Items]
Total liabilities	1,820.8	882.5
Securitization Vehicles | Other liabilities
Variable Interest Entity [Line Items]
Total liabilities	1.3	0.6
Other
Variable Interest Entity [Line Items]
Total assets	1.5	1.5
Total liabilities	0.2	0.2
Other | Cash
Variable Interest Entity [Line Items]
Total assets	1.2	1.1
Other | Financial instruments owned
Variable Interest Entity [Line Items]
Total assets	0.3	0.4
Other | Securities purchased under agreement to resell
Variable Interest Entity [Line Items]
Total assets	0.0	0.0
Other | Other secured financings
Variable Interest Entity [Line Items]
Total liabilities	0.0	0.0
Other | Other liabilities
Variable Interest Entity [Line Items]
Total liabilities	$ 0.2	$ 0.2