Investments - Jefferies Finance - Narrative (Detail) - USD ($) $ in Thousands	6 Months Ended
May 31, 2018	Nov. 30, 2017
Guarantee Obligations [Line Items]
Brokers, dealers and clearing organizations	$ 2,488,632	$ 2,514,838
Financial instruments owned, at fair value	15,705,657	14,193,352
Jefferies Finance, LLC
Guarantee Obligations [Line Items]
Equity commitment	750,000
Total committed equity capitalization of JFIN	1,500,000
Funded portion of equity commitment to subsidiary	687,500
Unfunded portion of equity commitment to subsidiary	$ 62,500
Extension period	1 year
Termination notice period	60 days
Funded portion of loan commitment	$ 0
Loan commitment	250,000
Brokers, dealers and clearing organizations	200
Financial instruments owned, at fair value		1,500
Jefferies Finance, LLC \| Corporate debt securities
Guarantee Obligations [Line Items]
Committed line of credit facility amount	500,000
Jefferies Finance, LLC \| Other Assets
Guarantee Obligations [Line Items]
Receivables under service agreement	49,900	$ 20,500
Jefferies Finance, LLC \| Accrued expense and other liabilities
Guarantee Obligations [Line Items]
Payables under service agreement	$ 14,100

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