Fair Value Disclosures - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 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	$ 127,500	$ 31,700	$ 148,500	$ 42,300
Transfers of assets from Level 3 to Level 2	33,700	79,500	14,600	89,000
Transfers of liabilities from Level 2 to Level 3	23,700	57,400	37,000	69,600
Transfers of liabilities from Level 3 to Level 2	98,600	105,400	98,500	63,200
Net gains/(losses) on Level 3 assets (realized and unrealized)	(39,500)	2,000	(69,800)	2,700
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	124,300	14,100	144,700	(42,800)
Aggregate fair value of loans and other receivables on nonaccrual status and/or 90 days or greater past due	175,800		175,800		$ 127,000
Loans and other receivables greater than 90 days past due	16,600		16,600		24,800
Cash and securities segregated and on deposit for regulatory purposes with clearing and depository organizations	668,925		668,925		796,797
Other ABS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	44,500	7,600	31,100	10,800
Transfers of assets from Level 3 to Level 2				22,300
Net gains/(losses) on Level 3 assets (realized and unrealized)	(2,380)	3,070	(2,848)	(1,014)
CDOs and CLOs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	29,600		22,900
Transfers of assets from Level 3 to Level 2	4,400	17,600		12,500
Net gains/(losses) on Level 3 assets (realized and unrealized)	(12,879)	(1,793)	(14,223)	(2,790)
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	20,700	11,300	33,500	15,700
Transfers of assets from Level 3 to Level 2		10,500	4,000
Transfers of liabilities from Level 2 to Level 3			10,800
Net gains/(losses) on Level 3 assets (realized and unrealized)	(4,891)	(2,753)	(8,600)	2,434
Investments at fair value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3	19,200
Transfers of assets from Level 3 to Level 2		39,800		40,200
Net gains/(losses) on Level 3 assets (realized and unrealized)	(10,805)	2,841	(30,496)	(1,162)
Corporate equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3			37,000
Transfers of assets from Level 3 to Level 2	26,200		7,300
Net gains/(losses) on Level 3 assets (realized and unrealized)	(5,319)	2,353	(12,860)	6,126
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	60	74	(216)	76
Net derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of liabilities from Level 2 to Level 3	11,400	41,500	26,200	58,700
Transfers of liabilities from Level 3 to Level 2	66,100	14,400	40,200
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	32,744	14,760	44,729	29,079
Structured notes
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of liabilities from Level 2 to Level 3	11,100	9,500		10,300
Transfers of liabilities from Level 3 to Level 2	31,900	91,000	57,300	52,300
Corporate debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers of assets from Level 2 to Level 3			18,300
Net gains/(losses) on Level 3 assets (realized and unrealized)	(1,480)	(587)	1,560	(389)
Net gains/(losses) on Level 3 liabilities (realized and unrealized)	23	$ 148	27	$ 382
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	$ 96,200		$ 96,200		$ 35,000