Derivative Financial Instruments - Remaining Contract Maturity of Fair Value of OTC Derivative Assets and Liabilities (Footnote) (Detail) $ in Millions	May. 31, 2015 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Exchange traded derivative assets	$ 94.1
Cash collateral received	190.4
Exchange traded derivative liabilities, with fair value	27.7
Cash collateral pledged	$ 290.1