Investments - Jefferies Finance - Narrative (Detail) - USD ($)	3 Months Ended
	Feb. 28, 2017	Feb. 29, 2016	Nov. 30, 2016
Guarantee Obligations [Line Items]
Equity commitment	$ 600,000,000
Total committed equity capitalization of JIFN	1,200,000,000
Funded portion of equity commitment to subsidiary	493,900,000
Unfunded portion of equity commitment to subsidiary	$ 106,100,000
Extension period	1 year
Termination notice period	60 days
Funded portion of loan commitment	$ 0		$ 0
Loan commitment	250,000,000		250,000,000
Unfunded commitment fees income	300,000	$ 300,000
Interest income	1,100,000	2,000
Commissions for conducting brokerage services	145,822,000	155,824,000
Investment banking revenue	408,021,000	230,930,000
Financial instruments sold, not yet purchased, at fair value	8,728,491,000		8,359,202,000
Corporate debt securities [Member]
Guarantee Obligations [Line Items]
Committed line of credit facility amount	500,000,000
Jefferies Finance, LLC [Member]
Guarantee Obligations [Line Items]
Net income (loss) in earnings	42,000,000	(44,700,000)
Net underwriting fees paid by JFIN related to originations of loans by JFIN	66,200,000	19,400,000
Fees paid to JFIN related to origination of loans by JFIN	2,100,000
Commissions for conducting brokerage services	2,700,000
Investment banking revenue	100,000	1,400,000
Administrative services provided	20,200,000	$ 21,100,000
Financial instruments sold, not yet purchased, at fair value	300,000		4,000
Other Assets [Member] | Jefferies Finance, LLC [Member]
Guarantee Obligations [Line Items]
Receivables under service agreement	$ 18,000,000
Accounts Payable and Accrued Liabilities [Member] | Jefferies Finance, LLC [Member]
Guarantee Obligations [Line Items]
Payables under service agreement			$ 5,800,000