Related Party Transactions - Summary of Interest Income, Other Revenues and Investment Income to Private Equity Related Funds (Detail) - Equity Method Investee - Equity Investments in Jefferies Capital Partners Related Funds - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2017	Aug. 31, 2016
Related Party Transaction [Line Items]
Other revenues and investment income (loss)	$ (373)	$ 6,048	$ (9,793)	$ (1,664)
Service charges	$ 200	$ 201	$ 523	$ 537