Derivative Financial Instruments - Remaining Contract Maturity of Fair Value of OTC Derivative Assets and Liabilities (Footnote) (Detail) $ in Millions	May 31, 2017 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Exchange traded derivative assets	$ 7.3
Cash collateral received	166.6
Exchange traded derivative liabilities, with fair value	313.9
Cash collateral pledged	$ 154.1