Investments - Jefferies Finance - Narrative (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2015	Aug. 31, 2014	Nov. 30, 2014
Guarantee Obligations [Line Items]
Equity commitments to JFIN	$ 600,000,000		$ 600,000,000
Total committed equity capitalization of JIFN	1,200,000,000		1,200,000,000
Funded portion of equity commitment to subsidiary	510,400,000		510,400,000
Unfunded portion of equity commitment to subsidiary	89,600,000		$ 89,600,000
Extension period			1 year
Termination notice period			60 days
Maturity date			Mar. 01, 2016
Funded portion of loan commitment	0		$ 0		$ 0
Loan commitment	250,000,000		250,000,000		350,000,000
Interest income	200,000	$ 300,000	700,000	$ 1,400,000
Unfunded commitment fees	400,000	400,000	1,200,000	1,500,000
Net underwriting fees paid by JFIN related to originations of loans by JFIN	53,300,000	53,700,000	108,800,000	139,800,000
Fees paid to JFIN related to origination of loans by JFIN	1,500,000	2,600,000	3,100,000	10,500,000
Placement fees	389,820,000	467,793,000	1,066,077,000	1,213,262,000
Revenue in Connection of Execution of JFIN CLO	172,284,000	159,085,000	512,714,000	488,526,000
Underwriting fees	0	0	1,300,000	4,200,000
Committed Advances [Member]
Guarantee Obligations [Line Items]
Committed line of credit facility amount	500,000,000		500,000,000
Discretionary Advances [Member]
Guarantee Obligations [Line Items]
Committed line of credit facility amount	1,000,000,000		1,000,000,000
Jefferies Finance, LLC [Member]
Guarantee Obligations [Line Items]
Net income earnings	47,200,000	58,000,000	109,400,000	116,200,000
Placement fees	0	700,000	3,100,000	700,000
Revenue in Connection of Execution of JFIN CLO		2,500,000		4,600,000
Administrative services provided	8,400,000	$ 6,500,000	43,300,000	$ 35,200,000
Receivables under service agreement	$ 122,500,000		$ 122,500,000		$ 41,500,000