Derivative Financial Instruments - Counterparty Credit Quality with Respect to Fair Value of OTC Derivatives Assets (Detail) $ in Thousands	May 31, 2017 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
A- or higher	$ 147,797
BBB- to BBB	56,371
BB or lower	74,164
Unrated	59,402
Total OTC derivative assets included in Financial instruments owned	$ 337,734

Fair value of OTC derivatives assets, counterparty credit quality BB or lower.

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Fair value of OTC derivatives assets, counterparty credit quality BBB- to BBB.

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Fair value of OTC derivatives assets, counterparty credit quality unrated.

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Fair Value Of Over Counter Derivatives Assets Counterparty Credit QualityA Or Higher

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OTC Derivative Assets Included In Financial Instruments Owned.

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