Variable Interest Entities - Summary of Securities Issued by Securitization (Detail) (Variable Interest Entity Not Primary Beneficiary [Member], USD $) In Millions, unless otherwise specified	Feb. 28, 2013		Nov. 30, 2012
Variable Interest Entity [Line Items]
Carrying Amount	$ 2,319.7		$ 2,456.5
Mortgage- and asset-backed securitization activity - Agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	1,300.4
Mortgage- and asset- backed securitization activity - Non-agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	938.1
Mortgage- and Asset-backed Vehicles [Member]
Variable Interest Entity [Line Items]
Carrying Amount	4,939.3
Collateralized loan obligations securitizations [Member]
Variable Interest Entity [Line Items]
Carrying Amount	24.5	[1]	5.3	[1]
Residential mortgage-backed securities [Member]
Variable Interest Entity [Line Items]
Carrying Amount	2,045.6
Commercial mortgage-backed securities [Member]
Variable Interest Entity [Line Items]
Carrying Amount	599.2
Collateralized debt obligations [Member]
Variable Interest Entity [Line Items]
Carrying Amount	20.3
Other asset-backed securities [Member]
Variable Interest Entity [Line Items]
Carrying Amount	11.2
Nonagency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	1,132.2
Nonagency [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	938.1
Nonagency [Member] | Collateralized loan obligations securitizations [Member]
Variable Interest Entity [Line Items]
Carrying Amount	24.5
Nonagency [Member] | Residential mortgage-backed securities [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	64.5
Nonagency [Member] | Commercial mortgage-backed securities [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	73.6
Nonagency [Member] | Collateralized debt obligations [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	20.3
Nonagency [Member] | Other asset-backed securities [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	11.2
Agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	3,807.1
Agency [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	1,300.4
Agency [Member] | Residential mortgage-backed securities [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	1,981.1
Agency [Member] | Commercial mortgage-backed securities [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	$ 525.6

[1] Consists of debt securities accounted for at fair value, which are included within Financial instruments owned.