Commitments, Contingencies and Guarantees - Commitments and Contingencies (Detail) (USD $) In Millions, unless otherwise specified	May 31, 2014
Commitments And Guarantee Obligations [Line Items]
2014	$ 1,166.5
2015	421.7
2016 and 2017	1,012.5
2018 and 2019	175.9
2020 and Later	475.4
Maximum Payout	3,252.0
Equity commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2014	1.6
2015	7.5
2016 and 2017	0.9
2018 and 2019
2020 and Later	475.4
Maximum Payout	485.4
Loan commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2014	10.8
2015	26.3
2016 and 2017	515.1
2018 and 2019	175.9
2020 and Later
Maximum Payout	728.1
Mortgage-related commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2014	862.0
2015	387.9
2016 and 2017	496.5
2018 and 2019
2020 and Later
Maximum Payout	1,746.4
Underwriting commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2014	85.9
2015
2016 and 2017
2018 and 2019
2020 and Later
Maximum Payout	85.9
Forward starting reverse repos and repos [Member]
Commitments And Guarantee Obligations [Line Items]
2014	206.2
2015
2016 and 2017
2018 and 2019
2020 and Later
Maximum Payout	$ 206.2