Derivative Financial Instruments - Counterparty Credit Quality with Respect to Fair Value of OTC Derivatives Assets (Details) $ in Thousands	Aug. 31, 2019 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
A- or higher	$ 146,495
BBB- to BBB	42,072
BB or lower	275,252
Unrated	204,913
Total OTC derivative assets included in Financial instruments owned	$ 668,732

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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