Commitments, Contingencies and Guarantees - Commitments and Contingencies (Detail) $ in Millions	Aug. 31, 2015 USD ($)
Commitments And Guarantee Obligations [Line Items]
2015	$ 3,190.0
2016	1,919.0
2017 and 2018	1,050.7
2019 and 2020	58.3
2021 and Later	269.4
Notional/ Maximum Payout	6,487.4
Equity commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	0.0
2016	9.9
2017 and 2018	0.0
2019 and 2020	0.0
2021 and Later	232.4
Notional/ Maximum Payout	242.3
Loan commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	5.0
2016	356.0
2017 and 2018	450.3
2019 and 2020	52.3
2021 and Later	0.0
Notional/ Maximum Payout	863.6
Mortgage-related and other purchase commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	472.4
2016	1,553.1
2017 and 2018	576.4
2019 and 2020	0.0
2021 and Later	0.0
Notional/ Maximum Payout	2,601.9
Forward starting reverse repos and repos [Member]
Commitments And Guarantee Obligations [Line Items]
2015	2,712.6
2016	0.0
2017 and 2018	0.0
2019 and 2020	0.0
2021 and Later	0.0
Notional/ Maximum Payout	2,712.6
Other unfunded commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	0.0
2016	0.0
2017 and 2018	24.0
2019 and 2020	6.0
2021 and Later	37.0
Notional/ Maximum Payout	$ 67.0