Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2015	May. 31, 2014	Nov. 30, 2014	Mar. 18, 2015
Related Party Transaction [Line Items]
Purchase commitments from Berkadia Commercial Mortgage, LLC			$ 336,500		$ 344,800
Commissions for conducting brokerage services	$ 173,508	$ 167,378	340,430	$ 329,441
Loans outstanding to certain employees	24,300		24,300		20,100
Noncontrolling interests	40,068		40,068		38,848
Leucadia [Member]
Related Party Transaction [Line Items]
Noncontrolling interests	26,100		26,100		25,400
Private Equity Related Funds [Member]
Related Party Transaction [Line Items]
Equity investments loans in related funds	36,700		36,700		60,700
Leucadia [Member]
Related Party Transaction [Line Items]
Revenue from related parties	6,100	$ 9,200	11,200	$ 17,200
Due to related party	7,300		7,300		41,500
Due from related party	3,000		3,000		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	0		200
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	$ 900		$ 1,300