Derivative Financial Instruments (Remaining Contract Maturity of Fair Value of OTC Derivative Assets and Liabilities) (Details) $ in Thousands	Aug. 31, 2020 USD ($)
OTC Derivative Assets
0-12 Months	$ 273,497
1-5 Years	304,574
Greater Than 5 Years	240,514
Cross- maturity netting	(89,613)
Total OTC derivative assets, net of cross-maturity netting	728,972
Cross product counterparty netting	(22,759)
Total OTC derivative assets included in Financial instruments owned, at fair value	706,213
OTC Derivative Liabilities
0-12 Months	173,451
1-5 Years	567,851
Greater Than 5 Years	229,335
Cross-maturity netting	(89,613)
Total	881,024
Cross product counterparty netting	(22,759)
Total OTC derivative liabilities included in Financial instruments sold, not yet purchased, at fair value	858,265
Exchange traded derivative assets and other credit agreements	25,100
Cash collateral received	201,600
Exchange traded derivative liabilities and other credit agreements	14,500
Cash collateral pledged	389,500
Commodity swaps, options and forwards
OTC Derivative Assets
0-12 Months	18,611
1-5 Years	6,836
Greater Than 5 Years	0
Cross- maturity netting	0
Total OTC derivative assets, net of cross-maturity netting	25,447
Equity options and forwards
OTC Derivative Assets
0-12 Months	21,437
1-5 Years	44,672
Greater Than 5 Years	15,160
Cross- maturity netting	(25,445)
Total OTC derivative assets, net of cross-maturity netting	55,824
OTC Derivative Liabilities
0-12 Months	15,474
1-5 Years	370,915
Greater Than 5 Years	156,839
Cross-maturity netting	(25,445)
Total	517,783
Credit default swaps
OTC Derivative Liabilities
0-12 Months	12
1-5 Years	1,108
Greater Than 5 Years	0
Cross-maturity netting	0
Total	1,120
Total return swaps
OTC Derivative Assets
0-12 Months	74,923
1-5 Years	19,764
Greater Than 5 Years	2,872
Cross- maturity netting	(14,666)
Total OTC derivative assets, net of cross-maturity netting	82,893
OTC Derivative Liabilities
0-12 Months	58,888
1-5 Years	103,567
Greater Than 5 Years	0
Cross-maturity netting	(14,666)
Total	147,789
Foreign currency forwards, swaps and options
OTC Derivative Assets
0-12 Months	63,570
1-5 Years	28,993
Greater Than 5 Years	0
Cross- maturity netting	(4,477)
Total OTC derivative assets, net of cross-maturity netting	88,086
OTC Derivative Liabilities
0-12 Months	55,541
1-5 Years	11,792
Greater Than 5 Years	34
Cross-maturity netting	(4,477)
Total	62,890
Fixed income forwards
OTC Derivative Liabilities
0-12 Months	1,404
1-5 Years	0
Greater Than 5 Years	0
Cross-maturity netting	0
Total	1,404
Interest rate swaps, options and forwards
OTC Derivative Assets
0-12 Months	94,956
1-5 Years	204,309
Greater Than 5 Years	222,482
Cross- maturity netting	(45,025)
Total OTC derivative assets, net of cross-maturity netting	476,722
OTC Derivative Liabilities
0-12 Months	42,132
1-5 Years	80,469
Greater Than 5 Years	72,462
Cross-maturity netting	(45,025)
Total	$ 150,038