Derivative Financial Instruments (Remaining Contract Maturity of Fair Value of OTC Derivative Assets and Liabilities) (Details) $ in Thousands	May 31, 2020 USD ($)
OTC Derivative Assets
0-12 Months	$ 299,879
1-5 Years	329,693
Greater Than 5 Years	271,928
Cross- maturity netting	(64,997)
Total OTC derivative assets, net of cross-maturity netting	836,503
Cross product counterparty netting	(37,469)
Total OTC derivative assets included in Financial instruments owned, at fair value	799,034
OTC Derivative Liabilities
0-12 Months	179,703
1-5 Years	403,210
Greater Than 5 Years	182,196
Cross-maturity netting	(64,997)
Total	700,112
Cross product counterparty netting	(37,469)
Total OTC derivative liabilities included in Financial instruments sold, not yet purchased, at fair value	662,643
Exchange traded derivative assets and other credit agreements	34,100
Cash collateral received	192,600
Exchange traded derivative liabilities and other credit agreements	102,400
Cash collateral pledged	347,100
Commodity swaps, options and forwards
OTC Derivative Assets
0-12 Months	44,360
1-5 Years	10,753
Greater Than 5 Years	0
Cross- maturity netting	0
Total OTC derivative assets, net of cross-maturity netting	55,113
Equity forwards, swaps and options
OTC Derivative Assets
0-12 Months	46,129
1-5 Years	200
Greater Than 5 Years	18,280
Cross- maturity netting	(13,218)
Total OTC derivative assets, net of cross-maturity netting	51,391
OTC Derivative Liabilities
0-12 Months	14,944
1-5 Years	251,025
Greater Than 5 Years	101,362
Cross-maturity netting	(13,218)
Total	354,113
Credit default swaps
OTC Derivative Assets
0-12 Months	11
1-5 Years	900
Greater Than 5 Years	133
Cross- maturity netting	(11)
Total OTC derivative assets, net of cross-maturity netting	1,033
OTC Derivative Liabilities
0-12 Months	0
1-5 Years	1,489
Greater Than 5 Years	69
Cross-maturity netting	(11)
Total	1,547
Total return swaps
OTC Derivative Assets
0-12 Months	83,333
1-5 Years	63,660
Greater Than 5 Years	0
Cross- maturity netting	(8,838)
Total OTC derivative assets, net of cross-maturity netting	138,155
OTC Derivative Liabilities
0-12 Months	61,841
1-5 Years	56,238
Greater Than 5 Years	0
Cross-maturity netting	(8,838)
Total	109,241
Foreign currency forwards, swaps and options
OTC Derivative Assets
0-12 Months	55,197
1-5 Years	11,655
Greater Than 5 Years	113
Cross- maturity netting	(6,611)
Total OTC derivative assets, net of cross-maturity netting	60,354
OTC Derivative Liabilities
0-12 Months	74,469
1-5 Years	10,196
Greater Than 5 Years	92
Cross-maturity netting	(6,611)
Total	78,146
Interest rate swaps, options and forwards
OTC Derivative Assets
0-12 Months	70,849
1-5 Years	242,525
Greater Than 5 Years	253,402
Cross- maturity netting	(36,319)
Total OTC derivative assets, net of cross-maturity netting	530,457
OTC Derivative Liabilities
0-12 Months	28,449
1-5 Years	84,262
Greater Than 5 Years	80,673
Cross-maturity netting	(36,319)
Total	$ 157,065