Derivative Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	Nov. 30, 2011
Remaining contract maturity of fair value of over the counter derivative assets
OTC derivative assets having maturity period of 0 to 12 months	$ 391,064
OTC derivative assets having maturity period of 1 to 5 years	83,817
OTC derivative assets having maturity period of greater than 5 years	131,729
OTC derivative assets cross maturity netting	(52,340)
Total	554,270
Cross product counterparty netting	(28,036)
Total OTC derivative assets included in Financial instruments owned	526,234
Remaining contract maturity of fair value of Over The Counter derivative liabilities
OTC derivative liabilities having maturity period of 0 to 12 months	300,297
OTC derivative liabilities having maturity period of 1 to 5 years	138,317
OTC derivative liabilities having maturity period of greater than 5 years	139,621
OTC derivative liabilities cross maturity netting	(52,340)
Total	525,895
Cross product counterparty netting	(28,036)
Total OTC derivative liabilities included in Financial instruments sold, not yet purchased	497,859
Commodity swaps, options and forwards [Member]
Remaining contract maturity of fair value of Over The Counter derivative liabilities
OTC derivative liabilities having maturity period of 0 to 12 months	94,225
OTC derivative liabilities having maturity period of 1 to 5 years	8,645
OTC derivative liabilities having maturity period of greater than 5 years	0
OTC derivative liabilities cross maturity netting	(1,152)
Total	101,748
Equity Options [Member]
Remaining contract maturity of fair value of Over The Counter derivative liabilities
OTC derivative liabilities having maturity period of 0 to 12 months	0
OTC derivative liabilities having maturity period of 1 to 5 years	5,256
OTC derivative liabilities having maturity period of greater than 5 years	0
OTC derivative liabilities cross maturity netting	0
Total	5,256
Credit default swap [Member]
Remaining contract maturity of fair value of Over The Counter derivative liabilities
OTC derivative liabilities having maturity period of 0 to 12 months	352
OTC derivative liabilities having maturity period of 1 to 5 years	2,053
OTC derivative liabilities having maturity period of greater than 5 years	1,546
OTC derivative liabilities cross maturity netting	(1,751)
Total	2,200
Total return swaps [Member]
Remaining contract maturity of fair value of Over The Counter derivative liabilities
OTC derivative liabilities having maturity period of 0 to 12 months	0
OTC derivative liabilities having maturity period of 1 to 5 years	1,004
OTC derivative liabilities having maturity period of greater than 5 years	0
OTC derivative liabilities cross maturity netting	0
Total	1,004
Foreign currency forwards, swaps and options [Member]
Remaining contract maturity of fair value of Over The Counter derivative liabilities
OTC derivative liabilities having maturity period of 0 to 12 months	176,369
OTC derivative liabilities having maturity period of 1 to 5 years	36,388
OTC derivative liabilities having maturity period of greater than 5 years	0
OTC derivative liabilities cross maturity netting	(15,162)
Total	197,595
Interest rate swaps and caps [Member]
Remaining contract maturity of fair value of Over The Counter derivative liabilities
OTC derivative liabilities having maturity period of 0 to 12 months	29,321
OTC derivative liabilities having maturity period of 1 to 5 years	84,971
OTC derivative liabilities having maturity period of greater than 5 years	138,075
OTC derivative liabilities cross maturity netting	(34,275)
Total	218,092
Commodity swaps, options and forwards [Member]
Remaining contract maturity of fair value of over the counter derivative assets
OTC derivative assets having maturity period of 0 to 12 months	202,723
OTC derivative assets having maturity period of 1 to 5 years	8,200
OTC derivative assets having maturity period of greater than 5 years	0
OTC derivative assets cross maturity netting	(1,152)
Total	209,771
Credit default swap [Member]
Remaining contract maturity of fair value of over the counter derivative assets
OTC derivative assets having maturity period of 0 to 12 months	0
OTC derivative assets having maturity period of 1 to 5 years	12,474
OTC derivative assets having maturity period of greater than 5 years	21,793
OTC derivative assets cross maturity netting	(1,751)
Total	32,516
Total return swaps [Member]
Remaining contract maturity of fair value of over the counter derivative assets
OTC derivative assets having maturity period of 0 to 12 months	23
OTC derivative assets having maturity period of 1 to 5 years	0
OTC derivative assets having maturity period of greater than 5 years	0
OTC derivative assets cross maturity netting	0
Total	23
Foreign currency forwards, swaps and options [Member]
Remaining contract maturity of fair value of over the counter derivative assets
OTC derivative assets having maturity period of 0 to 12 months	163,668
OTC derivative assets having maturity period of 1 to 5 years	38,919
OTC derivative assets having maturity period of greater than 5 years	0
OTC derivative assets cross maturity netting	(15,162)
Total	187,425
Fixed income forwards [Member]
Remaining contract maturity of fair value of over the counter derivative assets
OTC derivative assets having maturity period of 0 to 12 months	5,078
OTC derivative assets having maturity period of 1 to 5 years	0
OTC derivative assets having maturity period of greater than 5 years	0
OTC derivative assets cross maturity netting	0
Total	5,078
Interest rate swaps and caps [Member]
Remaining contract maturity of fair value of over the counter derivative assets
OTC derivative assets having maturity period of 0 to 12 months	19,572
OTC derivative assets having maturity period of 1 to 5 years	24,224
OTC derivative assets having maturity period of greater than 5 years	109,936
OTC derivative assets cross maturity netting	(34,275)
Total	$ 119,457