Fair Value Disclosures (Analysis of Level 3 Assets and Liabilities Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Nov. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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)	(42,800)	(5,100)
Net gains (losses) on Level 3 liabilities (realized and unrealized)	26,400	22,500
Excluded assets from unobservable quantitative information	157,900		$ 79,900
Excluded liabilities from unobservable quantitative information	3,600		$ 400
Loans and other receivables
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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)	(4,307)	814
Other asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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)
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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
Corporate equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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)	(8,280)	4,488
Net gains (losses) on Level 3 liabilities (realized and unrealized)	(291)	2
Investments at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gains (losses) on Level 3 assets (realized and unrealized)	(27,333)	(2,923)
Net derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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 and Liabilities Measured on Recurring and Nonrecurring Basis [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
Collateralized debt obligations and collateralized loan obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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)	$ (1,940)	$ (6,726)