Fair Value Disclosures - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Nov. 30, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	$ 85,300	$ 60,400
Transfers of assets from Level 3 to Level 2	16,800	41,200
Transfers of liabilities from Level 2 to Level 3	102,500	36,600
Transfers of liabilities from Level 3 to Level 2	107,400	12,900
Net gains/(losses) on Level 3 assets (realized and unrealized)	(37,900)	(4,500)
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	26,400	22,500
Aggregate fair value of loans and other receivables on nonaccrual status and/or 90 days or greater past due	230,200		$ 127,000
Loans and other receivables greater than 90 days past due	35,400		24,800
Cash and securities segregated and on deposit for regulatory purposes with clearing and depository organizations	742,134		796,797
Investments at fair value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net gains/(losses) on Level 3 assets (realized and unrealized)	(20,392)	(786)
Loans and other receivables
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	6,000	25,800
Transfers of assets from Level 3 to Level 2	4,900	6,500
Net gains/(losses) on Level 3 assets (realized and unrealized)	(3,781)	814
Corporate equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	55,400
Transfers of assets from Level 3 to Level 2	2,700
Net gains/(losses) on Level 3 assets (realized and unrealized)	(8,195)	4,830
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	(291)	2
Corporate debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	16,500
Net gains/(losses) on Level 3 assets (realized and unrealized)	1,269	466
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	189	241
Net derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of liabilities from Level 2 to Level 3	83,000	13,900
Transfers of liabilities from Level 3 to Level 2	37,300
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	17,528	5,348
Structured Notes
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of liabilities from Level 2 to Level 3	13,100	22,200
Transfers of liabilities from Level 3 to Level 2	69,100	9,400
CMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net gains/(losses) on Level 3 assets (realized and unrealized)	(306)	136
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	0	(70)
CDOs and CLOs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3		14,100
Transfers of assets from Level 3 to Level 2		15,700
Net gains/(losses) on Level 3 assets (realized and unrealized)	(2,069)	(8,153)
Other ABS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3		10,800
Transfers of assets from Level 3 to Level 2	6,300	12,600
Net gains/(losses) on Level 3 assets (realized and unrealized)	(4,159)	(2,290)
RMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net gains/(losses) on Level 3 assets (realized and unrealized)	(280)	462
Long-term debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of liabilities from Level 2 to Level 3		12,744
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	9,016	$ 16,701
US Treasury Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash and securities segregated and on deposit for regulatory purposes with clearing and depository organizations	$ 331,500		$ 35,000