Fair Value Disclosures - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2014
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Investments at fair value	$ 24,300	$ 36,700
Transfers of assets from Level 2 to Level 3	179,600	236,700	$ 139,000
Transfers of assets from Level 3 to Level 2	133,200	85,800	54,600
Net gains/(losses) on Level 3 assets (realized and unrealized)	(128,500)	(34,300)	(28,600)
Net gains (losses) on Level 3 liabilities (realized and unrealized)	1,900	8,300	(6,000)
Aggregate fair value of loans and other receivables	29,800	307,500
Loan and other receivables greater than 90 days past due	18,900	11,300
Cash and securities segregated and on deposit for regulatory purposes or deposited with clearing and depository organizations	857,337	751,084
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
Loan Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of liabilities from Level 3 to Level 2	10,500		1,000
Derivative liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of liabilities from Level 3 to Level 2			3,300
CDOs and CLOs [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	19,400	69,800	73,000
Transfers of assets from Level 3 to Level 2	15,400	34,900
Net gains/(losses) on Level 3 assets (realized and unrealized)	(14,918)	(66,332)	(6,386)
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	17,500	30,400	30,300
Transfers of assets from Level 3 to Level 2	26,800	16,300	22,400
Net gains/(losses) on Level 3 assets (realized and unrealized)	(9,612)	(12,951)	(9,870)
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	17,400	11,300	16,600
Transfers of assets from Level 3 to Level 2		6,300
Net gains/(losses) on Level 3 assets (realized and unrealized)	(7,550)	(3,813)	(4,237)
Municipal securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	28,700	21,500
Net gains/(losses) on Level 3 assets (realized and unrealized)	(1,462)	10
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	16,900
Transfers of assets from Level 3 to Level 2	26,800
Net gains/(losses) on Level 3 assets (realized and unrealized)	(14,381)	(990)	1,784
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	13,800	20,100	8,500
Transfers of assets from Level 3 to Level 2	37,800	4,700	3,500
Net gains/(losses) on Level 3 assets (realized and unrealized)	(42,566)	(14,755)	(31,311)
Corporate debt securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3	28,100	7,400
Transfers of assets from Level 3 to Level 2			7,500
Net gains/(losses) on Level 3 assets (realized and unrealized)	(16,230)	(11,013)	6,629
Corporate equity securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Transfers of assets from Level 2 to Level 3			9,700
Transfers of assets from Level 3 to Level 2	19,200	7,700	4,900
Net gains/(losses) on Level 3 assets (realized and unrealized)	(8,463)	11,154	957
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	31,900	74,700
Transfers of assets from Level 3 to Level 2		15,800	15,500
Net gains/(losses) on Level 3 assets (realized and unrealized)	$ (13,278)	64,380	$ 13,781
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% 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%
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]
Asset reported NAV or percentage of reported enterprise fair value	$ 131,500	156,200
Liability reported NAV or percentage of reported enterprise fair value	1,600	$ 600
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Cash and securities segregated and on deposit for regulatory purposes or deposited with clearing and depository organizations	$ 99,900