Variable Interest Entities (Details 1) (USD $) In Millions, unless otherwise specified	Feb. 29, 2012	Nov. 30, 2011
Mortgage- and asset-backed vehicles - Agency [Member]
Total assets, maximum exposure to loss and carrying amount of interests in non consolidated VIE
Carrying Amount	$ 1,413.5
Mortgage- and asset-backed vehicles - Non-agency [Member]
Total assets, maximum exposure to loss and carrying amount of interests in non consolidated VIE
Carrying Amount	466.5
Variable Interest Entity Not Primary Beneficiary [Member]
Total assets, maximum exposure to loss and carrying amount of interests in non consolidated VIE
VIE Assets	61,312.6	51,218.9
Maximum exposure to loss in non-consolidated VIEs	2,056.7	2,177.1
Carrying Amount	1,998.1	2,110.3
Variable Interest Entity Not Primary Beneficiary [Member] | Collateralized loan obligations [Member]
Total assets, maximum exposure to loss and carrying amount of interests in non consolidated VIE
VIE Assets	1,753.2	1,768.4
Maximum exposure to loss in non-consolidated VIEs	48.4	48.2
Carrying Amount	48.4	48.2
Variable Interest Entity Not Primary Beneficiary [Member] | Mortgage- and asset-backed vehicles - Agency [Member]
Total assets, maximum exposure to loss and carrying amount of interests in non consolidated VIE
VIE Assets	7,483.1	6,523.0
Maximum exposure to loss in non-consolidated VIEs	1,413.5	1,410.9
Carrying Amount	1,413.5	1,410.9
Variable Interest Entity Not Primary Beneficiary [Member] | Mortgage- and asset-backed vehicles - Non-agency [Member]
Total assets, maximum exposure to loss and carrying amount of interests in non consolidated VIE
VIE Assets	51,082.5	41,939.4
Maximum exposure to loss in non-consolidated VIEs	466.5	583.9
Carrying Amount	466.5	583.9
Variable Interest Entity Not Primary Beneficiary [Member] | Asset management vehicle [Member]
Total assets, maximum exposure to loss and carrying amount of interests in non consolidated VIE
VIE Assets	895.8	903.9
Maximum exposure to loss in non-consolidated VIEs	3.0	2.8
Carrying Amount	3.0	2.8
Variable Interest Entity Not Primary Beneficiary [Member] | Private equity vehicles [Member]
Total assets, maximum exposure to loss and carrying amount of interests in non consolidated VIE
VIE Assets	98.0	84.2
Maximum exposure to loss in non-consolidated VIEs	125.3	131.3
Carrying Amount	$ 66.7	$ 64.5