Variable Interest Entities - Assets and Liabilities of Consolidated VIEs Prior to Consolidation (Detail) - USD ($) $ in Millions	Feb. 28, 2018	Nov. 30, 2017
Securitization Vehicles
Variable Interest Entity [Line Items]
Assets	$ 710.0	$ 773.6
Liabilities	709.3	772.1
Secured financing included in inventory and eliminated	8.0	44.1
Securitization Vehicles | Cash
Variable Interest Entity [Line Items]
Assets	4.0	6.5
Securitization Vehicles | Financial instruments owned
Variable Interest Entity [Line Items]
Assets	1.1	37.6
Securitization Vehicles | Securities purchased under agreement to resell
Variable Interest Entity [Line Items]
Assets	704.9	729.3
Securitization Vehicles | Fees, interest and other receivables
Variable Interest Entity [Line Items]
Assets	0.0	0.2
Securitization Vehicles | Other secured financings
Variable Interest Entity [Line Items]
Liabilities	706.5	766.2
Securitization Vehicles | Other liabilities
Variable Interest Entity [Line Items]
Liabilities	2.8	5.9
Other
Variable Interest Entity [Line Items]
Assets	1.5	1.5
Liabilities	0.2	0.2
Other | Cash
Variable Interest Entity [Line Items]
Assets	1.1	1.1
Other | Financial instruments owned
Variable Interest Entity [Line Items]
Assets	0.4	0.4
Other | Securities purchased under agreement to resell
Variable Interest Entity [Line Items]
Assets	0.0	0.0
Other | Fees, interest and other receivables
Variable Interest Entity [Line Items]
Assets	0.0	0.0
Other | Other secured financings
Variable Interest Entity [Line Items]
Liabilities	0.0	0.0
Other | Other liabilities
Variable Interest Entity [Line Items]
Liabilities	$ 0.2	$ 0.2