Variable Interest Entities - Non-Consolidated Variable Interest Entities (Detail) (USD $) In Millions, unless otherwise specified	Feb. 28, 2013		Nov. 30, 2012
Agency mortgage- and asset-backed securitizations [Member]
Variable Interest Entity [Line Items]
Financial Statement Carrying Amount	$ 1,300.4
Non-agency mortgage- and asset-backed securitizations [Member]
Variable Interest Entity [Line Items]
Financial Statement Carrying Amount	938.1
Variable Interest Entity Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Financial Statement Carrying Amount	2,319.7		2,456.5
Maximum exposure to loss in non-consolidated VIEs	2,362.7		2,509.2
VIE Assets	71,749.1		61,919.9
Variable Interest Entity Not Primary Beneficiary [Member] | Collateralized loan obligations securitizations [Member]
Variable Interest Entity [Line Items]
Financial Statement Carrying Amount	24.5	[1]	5.3	[1]
Maximum exposure to loss in non-consolidated VIEs	24.5	[2]	5.3	[2]
VIE Assets	1,231.0		499.7
Variable Interest Entity Not Primary Beneficiary [Member] | Agency mortgage- and asset-backed securitizations [Member]
Variable Interest Entity [Line Items]
Financial Statement Carrying Amount	1,300.4	[1],[3]	1,579.1	[1],[4]
Maximum exposure to loss in non-consolidated VIEs	1,300.4	[2],[3]	1,579.1	[2],[4]
VIE Assets	9,160.4	[3]	6,396.6	[4]
Variable Interest Entity Not Primary Beneficiary [Member] | Non-agency mortgage- and asset-backed securitizations [Member]
Variable Interest Entity [Line Items]
Financial Statement Carrying Amount	938.1	[1],[3]	814.1	[1],[4]
Maximum exposure to loss in non-consolidated VIEs	938.1	[2],[3]	814.1	[2],[4]
VIE Assets	60,800.9	[3]	54,436.2	[4]
Variable Interest Entity Not Primary Beneficiary [Member] | Asset management vehicle [Member]
Variable Interest Entity [Line Items]
Financial Statement Carrying Amount	2.9	[5]	3.0	[5]
Maximum exposure to loss in non-consolidated VIEs	2.9	[2]	3.0	[2]
VIE Assets	477.7		505.3
Variable Interest Entity Not Primary Beneficiary [Member] | Private equity vehicles [Member]
Variable Interest Entity [Line Items]
Financial Statement Carrying Amount	53.8	[5]	55.0	[5]
Maximum exposure to loss in non-consolidated VIEs	96.8		107.7
VIE Assets	$ 79.1		$ 82.1

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

[2] Our maximum exposure to loss in these non-consolidated VIEs is limited to our investment, which is represented by the financial statement carrying amount of our purchased or retained interests.

[3] VIE assets represent the unpaid principal balance of the assets in these vehicles at February 28, 2013 and represent the underlying assets that provide the cash flows supporting our variable interests.

[4] VIE assets represent the unpaid principal balance of the assets in these vehicles at November 30, 2012 and represent the underlying assets that provide the cash flows supporting our variable interests.

[5] Consists of equity interests and loans, which are included within Investments in managed funds and Loans to and investments in related parties.