Investments - Jefferies Finance - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2016	Aug. 31, 2015	Aug. 31, 2016	Aug. 31, 2015	Nov. 30, 2015
Guarantee Obligations [Line Items]
Equity commitments to JFIN	$ 600,000		$ 600,000
Total committed equity capitalization of JIFN	1,200,000		1,200,000
Funded portion of equity commitment to subsidiary	497,400		497,400
Unfunded portion of equity commitment to subsidiary	102,600		$ 102,600
Extension period			1 year
Termination notice period			60 days
Funded portion of loan commitment	0		$ 0		$ 19,300
Loan commitment	250,000		250,000		250,000
Commissions for conducting brokerage services	152,044	$ 172,284	454,025	$ 512,714
Recognized underwriting fees				1,300
Investment banking revenue (loss)	294,930	389,820	778,906	1,066,077
Jefferies Finance, LLC [Member]
Guarantee Obligations [Line Items]
Net income (loss) in earnings	(22,800)	47,800	(55,000)	109,800
Net underwriting fees paid by JFIN related to originations of loans by JFIN	19,000	53,300	42,100	108,800
Fees paid to JFIN related to origination of loans by JFIN		1,500	1,600	3,100
Commissions for conducting brokerage services		1,300	1,300	3,100
Administrative services provided	7,200	$ 8,400	35,800	$ 43,300
Receivables under service agreement	0		0		$ 7,800
Corporate debt securities [Member]
Guarantee Obligations [Line Items]
Committed line of credit facility amount	$ 500,000		$ 500,000