Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2015	Aug. 31, 2014	Nov. 30, 2014	Mar. 18, 2015
Related Party Transaction [Line Items]
Purchase commitments from Berkadia Commercial Mortgage, LLC			$ 412,000		$ 344,800
Commissions for conducting brokerage services	$ 172,284	$ 159,085	512,714	$ 488,526
Loans outstanding to certain employees	28,600		28,600		20,100
Noncontrolling interests	32,302		32,302		38,848
Leucadia [Member]
Related Party Transaction [Line Items]
Noncontrolling interests	26,200		26,200		25,400
Fair value of equity position			124,400
Private Equity Related Funds [Member]
Related Party Transaction [Line Items]
Equity investments loans in related funds	38,000		38,000		60,700
Leucadia [Member]
Related Party Transaction [Line Items]
Revenue from related parties	11,000	$ 9,000	22,200	$ 26,200
Due to related party	4,000		4,000		41,500
Due from related party	5,100		5,100		10,900
National Beef Packaging Company, LLC [Member]
Related Party Transaction [Line Items]
Due to related party	0		0		4,100
Commissions for conducting brokerage services	100		300
Harbinger Group Inc [Member]
Related Party Transaction [Line Items]
Unsettled purchases and sales of loans	266,600		266,600		$ 232,000
Number of shares sold of investment						18.6
Investment Banking [Member] | Harbinger Group Inc [Member]
Related Party Transaction [Line Items]
Revenue from related parties	0		1,300
Other Assets [Member] | Leucadia [Member]
Related Party Transaction [Line Items]
Tax receivable	$ 65,200		$ 65,200