Derivative Financial Instruments - Counterparty Credit Quality with Respect to Fair Value of OTC Derivatives Assets (Detail) $ in Thousands	Nov. 30, 2015 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair value of OTC derivatives assets, Counterparty credit quality, A- or higher	$ 188,146
Fair value of OTC derivatives assets, Counterparty credit quality, BBB- to BBB+	76,471
Fair value of OTC derivatives assets, Counterparty credit quality, BB+ or lower	50,581
Fair value of OTC derivatives assets, Counterparty credit quality, Unrated	59,934
Total OTC derivative assets included in Financial instruments owned	$ 375,132