Variable Interest Entities - Assets and Liabilities of Consolidated VIEs Prior to Consolidation (Detail) - USD ($) $ in Millions	Nov. 30, 2016	Nov. 30, 2015
Securitization Vehicles [Member]
Variable Interest Entity [Line Items]
Assets	$ 837.7	$ 786.4
Liabilities	837.2	786.4
Other [Member]
Variable Interest Entity [Line Items]
Assets	1.3	2.3
Liabilities	0.2	0.3
Cash [Member] | Securitization Vehicles [Member]
Variable Interest Entity [Line Items]
Assets	16.1	0.5
Cash [Member] | Other [Member]
Variable Interest Entity [Line Items]
Assets	0.7	1.5
Financial Instruments Owned [Member] | Securitization Vehicles [Member]
Variable Interest Entity [Line Items]
Assets	86.6	68.3
Financial Instruments Owned [Member] | Other [Member]
Variable Interest Entity [Line Items]
Assets	0.6	0.6
Securities Purchased Under Agreement to Resell [Member] | Securitization Vehicles [Member]
Variable Interest Entity [Line Items]
Assets	733.5	717.3
Securities Purchased Under Agreement to Resell [Member] | Other [Member]
Variable Interest Entity [Line Items]
Assets	0.0	0.0
Fees, Interest and Other Receivables [Member] | Securitization Vehicles [Member]
Variable Interest Entity [Line Items]
Assets	1.5	0.3
Fees, Interest and Other Receivables [Member] | Other [Member]
Variable Interest Entity [Line Items]
Assets	0.0	0.2
Other Secured Financings [Member] | Securitization Vehicles [Member]
Variable Interest Entity [Line Items]
Liabilities	813.1	785.0
Other Secured Financings [Member] | Other [Member]
Variable Interest Entity [Line Items]
Liabilities	0.0	0.0
Other Liabilities [Member] | Securitization Vehicles [Member]
Variable Interest Entity [Line Items]
Liabilities	24.1	1.4
Other Liabilities [Member] | Other [Member]
Variable Interest Entity [Line Items]
Liabilities	$ 0.2	$ 0.3