Commitments, Contingencies and Guarantees - Credit Exposure from Loan Commitments (Detail) (USD $) In Millions, unless otherwise specified	Feb. 28, 2015
Commitments And Guarantee Obligations [Line Items]
2015	$ 128.0
2016-2020	810.6
2021 and Later	0
Total Corporate Lending Exposure	938.6
Corporate Lending Exposure at Fair Value	235.1
Corporate Lending Commitments	703.5
Non-investment grade [Member]
Commitments And Guarantee Obligations [Line Items]
2015	0
2016-2020	167.6
2021 and Later	0
Total Corporate Lending Exposure	167.6
Corporate Lending Exposure at Fair Value	2.8
Corporate Lending Commitments	164.8
Unrated [Member]
Commitments And Guarantee Obligations [Line Items]
2015	128.0
2016-2020	643.0
2021 and Later	0
Total Corporate Lending Exposure	771.0
Corporate Lending Exposure at Fair Value	232.3
Corporate Lending Commitments	$ 538.7