Fair Value Disclosures - Additional Information (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
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Investments at fair value	$ 29,500		$ 29,500		$ 36,700
Transfers of assets from Level 2 to Level 3	147,000	$ 73,400	157,800	$ 157,700
Transfers of assets from Level 3 to Level 2	91,800	91,400	114,500	88,100
Transfers of liabilities from Level 2 to Level 3		2,500
Transfers of liabilities from Level 3 to Level 2		51,600	10,200	51,600
Net gains/(losses) on Level 3 assets (realized and unrealized)	(48,300)	64,900	(93,100)	48,500
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	5,400	1,700	(2,800)	(2,300)
Unadjusted net asset value of the funds	91,800		91,800		156,200
Unadjusted net liability value of the funds	1,700		1,700		600
Loan and other receivables on nonaccrual status	55,100		55,100		307,500
Aggregate fair value of loans and other receivables	19,100		19,100		$ 11,300
Long-term Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other changes in fair value	3,225	0	13,530	0
Long-term Debt [Member] | Principal Transactions Revenue [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other changes in fair value	4,500		15,200
Long-term Debt [Member] | Interest Expense [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other changes in fair value	1,300		1,700
CDOs and CLOs [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	23,700	42,800	16,900	16,000
Transfers of assets from Level 3 to Level 2	27,300	39,900	25,300	25,600
Net gains/(losses) on Level 3 assets (realized and unrealized)	(4,067)	(12,560)	(24,356)	(28,999)
Municipal securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	34,300		28,700
Net gains/(losses) on Level 3 assets (realized and unrealized)	(7,074)		(1,462)
RMBS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	13,700	17,800	21,700	21,300
Transfers of assets from Level 3 to Level 2	18,300	18,500	25,500	15,900
Net gains/(losses) on Level 3 assets (realized and unrealized)	(2,343)	(3,009)	(7,243)	(6,776)
Investments at fair value [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	29,000		26,100	76,200
Transfers of assets from Level 3 to Level 2		21,000		22,700
Net gains/(losses) on Level 3 assets (realized and unrealized)	(966)	83,580	(19,055)	88,195
Other asset-backed securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	27,300		38,500	1,400
Transfers of assets from Level 3 to Level 2			17,000
Net gains/(losses) on Level 3 assets (realized and unrealized)	(2,247)	870	(2,420)	666
Corporate equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3				1,600
Transfers of assets from Level 3 to Level 2	20,500	1,900	19,200	11,800
Net gains/(losses) on Level 3 assets (realized and unrealized)	(6,492)	3,901	(8,388)	10,247
Commercial mortgage-backed securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3		3,700	17,200	9,800
Transfers of assets from Level 3 to Level 2		5,200		5,600
Net gains/(losses) on Level 3 assets (realized and unrealized)	(1,531)	(510)	(4,606)	(2,053)
Loans and other receivables [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3		4,100		19,200
Transfers of assets from Level 3 to Level 2	15,800	3,500	19,800	6,100
Net gains/(losses) on Level 3 assets (realized and unrealized)	(23,445)	(2,111)	(30,843)	(7,331)
Corporate debt securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3		5,000		12,200
Net gains/(losses) on Level 3 assets (realized and unrealized)	$ (145)	$ (5,276)	$ 5,239	$ (5,425)
3.875% Convertible Senior Debentures due 2029 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt instrument interest rate	3.875%		3.875%
3.875% Convertible Senior Debentures due 2029 [Member] | Leucadia [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt instrument interest rate	3.875%		3.875%
Long-term debt embedded conversion option [Member] | Leucadia [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Volatility curve used in valuing embedded option			252 days