Fair Value Disclosures - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Feb. 28, 2013	Nov. 30, 2013	Nov. 30, 2015	Nov. 30, 2014	Mar. 01, 2013
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments at fair value			$ 36,700,000	$ 42,200,000
Other secured financings			762,909,000	605,824,000
Transfers of assets from Level 2 to Level 3	$ 100,500,000	$ 82,400,000	236,700,000	139,000,000
Transfers of assets from Level 3 to Level 2	112,700,000	55,900,000	85,800,000	54,600,000
Transfers of liabilities from Level 2 to Level 3	0	0
Net gains/(losses) on Level 3 assets (realized and unrealized)	13,200,000	(3,400,000)	(34,300,000)	(28,600,000)
Total gains/ losses (realized and unrealized)	(2,700,000)	1,100,000	8,300,000	(6,000,000)
Unadjusted net asset value of the funds			156,200,000	137,800,000
Unadjusted net liability value of the funds			600,000	300,000
Aggregate fair value of loans and other receivables			11,300,000	0
Loan and other receivables on nonaccrual status			307,500,000	274,600,000
Other Secured Financings [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of liabilities from Level 3 to Level 2			51,600,000
Loan Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of liabilities from Level 3 to Level 2				1,000,000
Derivative liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of liabilities from Level 3 to Level 2	700,000	100,000		3,300,000
Collateralized debt obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	5,300,000	2,800,000	69,800,000	73,000,000
Transfers of assets from Level 3 to Level 2	2,400,000	600,000	34,900,000
Residential mortgage-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	78,400,000	58,800,000	30,400,000	30,300,000
Transfers of assets from Level 3 to Level 2	73,500,000	45,900,000	16,300,000	22,400,000
Commercial mortgage-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	1,300,000		11,300,000	16,600,000
Transfers of assets from Level 3 to Level 2	10,900,000	2,200,000	6,300,000
Municipal securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3			21,500,000
Other asset-backed securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3		16,400,000
Transfers of assets from Level 3 to Level 2	200,000	1,100,000
Loans and other receivables [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	4,800,000	800,000	20,100,000	8,500,000
Transfers of assets from Level 3 to Level 2	19,900,000	1,700,000	4,700,000	3,500,000
Corporate debt securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	10,800,000	200,000	7,400,000
Transfers of assets from Level 3 to Level 2		800,000		7,500,000
Corporate equity securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	100,000	2,300,000		9,700,000
Transfers of assets from Level 3 to Level 2	$ 4,700,000	3,600,000	7,700,000	4,900,000
Investments at fair value [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3		$ 1,000,000	74,700,000
Transfers of assets from Level 3 to Level 2			$ 15,800,000	15,500,000
3.875% Convertible Senior Debentures due 2029 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Debt instrument interest rate			3.875%		3.875%
3.875% Convertible Senior Debentures due 2029 [Member] | Leucadia [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Debt instrument interest rate			3.875%		3.875%
Debt instrument maturity year			Nov. 01, 2029
Volatility curve used in valuing embedded option			252 days
Embedded conversion option [Member] | Leucadia [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Debt instrument maturity year			Nov. 01, 2017
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Other secured financings			$ 0	$ 7,800,000