Variable Interest Entities - Summary of Securities Issued by Securitization Vehicles (Detail) (Variable Interest Entity Not Primary Beneficiary [Member], USD $) In Millions, unless otherwise specified	Nov. 30, 2013
Mortgage- and asset-backed securitization activity - Agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	$ 1,226.0
Mortgage- and asset- backed securitization activity - Non-agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	840.1
Mortgage- and Asset-backed Vehicles [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	4,473.1
Collateralized loan obligations securitizations [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	11.9
Residential mortgage-backed securities [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	1,723.3
Commercial mortgage-backed securities [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	609.8
Collateralized debt obligations [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	27.9
Other asset-backed securities [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	34.1
Nonagency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	997.0
Nonagency [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount
Nonagency [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	840.1
Nonagency [Member] | Collateralized loan obligations securitizations [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	11.9
Nonagency [Member] | Residential mortgage-backed securities [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	55.1
Nonagency [Member] | Commercial mortgage-backed securities [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	27.9
Nonagency [Member] | Collateralized debt obligations [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	27.9
Nonagency [Member] | Other asset-backed securities [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	34.1
Agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	3,476.1
Agency [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	1,226.0
Agency [Member] | Mortgage- and asset- backed securitization activity - Non-agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount
Agency [Member] | Collateralized loan obligations securitizations [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount
Agency [Member] | Residential mortgage-backed securities [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	1,668.2
Agency [Member] | Commercial mortgage-backed securities [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount	581.9
Agency [Member] | Collateralized debt obligations [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount
Agency [Member] | Other asset-backed securities [Member] | Mortgage- and asset-backed securitization activity - Agency [Member]
Assets and Liabilities of Consolidated VIEs [Line Items]
Carrying Amount