Derivative Financial Instruments - Remaining Contract Maturity of Fair Value of OTC Derivative Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Feb. 28, 2013
Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities [Line Items]
OTC derivative assets having maturity period of 0 to 12 months	$ 166,170
OTC derivative assets having maturity period of 1 to 5 years	84,285	[1],[2],[3]
OTC derivative assets having maturity period of greater than 5 years	180,004	[1],[2],[3]
OTC derivative assets cross-maturity netting	(86,252)	[1],[2],[3],[4]
Total OTC derivative assets, net of cross-maturity netting	344,207
Cross product counterparty netting	(1,511)
Total OTC derivative assets included in Financial instruments owned	342,696	[5]
OTC derivative liabilities having maturity period of 0 to 12 months	207,446
OTC derivative liabilities having maturity period of 1 to 5 years	169,298	[1],[6],[7]
OTC derivative liabilities having maturity period of greater than 5 years	210,771	[1],[6],[7]
OTC derivative liabilities cross-maturity netting	(86,252)	[1],[4],[6],[7]
Total OTC derivative liabilities, net of cross-maturity netting	501,263
Cross product counterparty netting	(1,511)
Total OTC derivative liabilities included in Financial instruments sold, not yet purchased	499,752
Commodity swaps, options and forwards [Member]
Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities [Line Items]
OTC derivative assets having maturity period of 0 to 12 months	61,023
OTC derivative assets having maturity period of 1 to 5 years	137	[1],[2],[3]
OTC derivative assets having maturity period of greater than 5 years		[1],[2],[3]
OTC derivative assets cross-maturity netting	(318)	[1],[2],[3],[4]
Total OTC derivative assets, net of cross-maturity netting	60,842
OTC derivative liabilities having maturity period of 0 to 12 months	107,646
OTC derivative liabilities having maturity period of 1 to 5 years	108	[1],[6],[7]
OTC derivative liabilities having maturity period of greater than 5 years		[1],[6],[7]
OTC derivative liabilities cross-maturity netting	(318)	[1],[4],[6],[7]
Total OTC derivative liabilities, net of cross-maturity netting	107,436
Credit default swaps [Member]
Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities [Line Items]
OTC derivative assets having maturity period of 0 to 12 months
OTC derivative assets having maturity period of 1 to 5 years	3,844	[1],[2],[3]
OTC derivative assets having maturity period of greater than 5 years		[1],[2],[3]
OTC derivative assets cross-maturity netting		[1],[2],[3],[4]
Total OTC derivative assets, net of cross-maturity netting	3,844
OTC derivative liabilities having maturity period of 0 to 12 months	238
OTC derivative liabilities having maturity period of 1 to 5 years	7,014	[1],[6],[7]
OTC derivative liabilities having maturity period of greater than 5 years		[1],[6],[7]
OTC derivative liabilities cross-maturity netting		[1],[4],[6],[7]
Total OTC derivative liabilities, net of cross-maturity netting	7,252
Equity options [Member]
Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities [Line Items]
OTC derivative assets having maturity period of 0 to 12 months	1,622
OTC derivative assets having maturity period of 1 to 5 years		[1],[2],[3]
OTC derivative assets having maturity period of greater than 5 years		[1],[2],[3]
OTC derivative assets cross-maturity netting		[1],[2],[3],[4]
Total OTC derivative assets, net of cross-maturity netting	1,622
OTC derivative liabilities having maturity period of 0 to 12 months	3,148
OTC derivative liabilities having maturity period of 1 to 5 years		[1],[6],[7]
OTC derivative liabilities having maturity period of greater than 5 years		[1],[6],[7]
OTC derivative liabilities cross-maturity netting		[1],[4],[6],[7]
Total OTC derivative liabilities, net of cross-maturity netting	3,148
Total return swaps [Member]
Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities [Line Items]
OTC derivative assets having maturity period of 0 to 12 months	1,277
OTC derivative assets having maturity period of 1 to 5 years		[1],[2],[3]
OTC derivative assets having maturity period of greater than 5 years		[1],[2],[3]
OTC derivative assets cross-maturity netting		[1],[2],[3],[4]
Total OTC derivative assets, net of cross-maturity netting	1,277
OTC derivative liabilities having maturity period of 0 to 12 months	6,248
OTC derivative liabilities having maturity period of 1 to 5 years		[1],[6],[7]
OTC derivative liabilities having maturity period of greater than 5 years		[1],[6],[7]
OTC derivative liabilities cross-maturity netting		[1],[4],[6],[7]
Total OTC derivative liabilities, net of cross-maturity netting	6,248
Foreign currency forwards, swaps and options [Member]
Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities [Line Items]
OTC derivative assets having maturity period of 0 to 12 months	82,784
OTC derivative assets having maturity period of 1 to 5 years	32,781	[1],[2],[3]
OTC derivative assets having maturity period of greater than 5 years		[1],[2],[3]
OTC derivative assets cross-maturity netting	(8,301)	[1],[2],[3],[4]
Total OTC derivative assets, net of cross-maturity netting	107,264
OTC derivative liabilities having maturity period of 0 to 12 months	73,554
OTC derivative liabilities having maturity period of 1 to 5 years	31,197	[1],[6],[7]
OTC derivative liabilities having maturity period of greater than 5 years		[1],[6],[7]
OTC derivative liabilities cross-maturity netting	(8,301)	[1],[4],[6],[7]
Total OTC derivative liabilities, net of cross-maturity netting	96,450
Fixed income forwards [Member]
Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities [Line Items]
OTC derivative assets having maturity period of 0 to 12 months
OTC derivative assets having maturity period of 1 to 5 years		[1],[2],[3]
OTC derivative assets having maturity period of greater than 5 years	447	[1],[2],[3]
OTC derivative assets cross-maturity netting		[1],[2],[3],[4]
Total OTC derivative assets, net of cross-maturity netting	447
Interest rate swaps and options [Member]
Remaining Contract Maturity Of Fair Value Of Over Counter Derivative Assets And Liabilities [Line Items]
OTC derivative assets having maturity period of 0 to 12 months	19,464
OTC derivative assets having maturity period of 1 to 5 years	47,523	[1],[2],[3]
OTC derivative assets having maturity period of greater than 5 years	179,557	[1],[2],[3]
OTC derivative assets cross-maturity netting	(77,633)	[1],[2],[3],[4]
Total OTC derivative assets, net of cross-maturity netting	168,911
OTC derivative liabilities having maturity period of 0 to 12 months	16,612
OTC derivative liabilities having maturity period of 1 to 5 years	130,979	[1],[6],[7]
OTC derivative liabilities having maturity period of greater than 5 years	210,771	[1],[6],[7]
OTC derivative liabilities cross-maturity netting	(77,633)	[1],[4],[6],[7]
Total OTC derivative liabilities, net of cross-maturity netting	$ 280,729

[1] Derivative fair values include counterparty netting within product category.

[2] At February 28, 2013, we held exchange traded derivative assets and other credit enhancements with a fair value of $20.5 million, which are not included in this table.

[3] OTC derivative assets in the table above are gross of collateral received. OTC derivative assets are recorded net of collateral received on the Consolidated Statements of Financial Condition. At February 28, 2013, cash collateral received was $156.3 million.

[4] Amounts represent the netting of receivable balances with payable balances for the same counterparty within product category across maturity categories.

[5] We utilize internal credit ratings determined by our Credit Risk Management. Credit ratings determined by Credit Risk Management use methodologies that produce ratings generally consistent with those produced by external rating agencies.

[6] OTC derivative liabilities in the table above are gross of collateral pledged. OTC derivative liabilities are recorded net of collateral pledged on the Consolidated Statements of Financial Condition. At February 28, 2013, cash collateral pledged was $292.6 million.

[7] At February 28, 2013, we held exchange traded derivative liabilities and other credit enhancements with a fair value of $13.5 million, which are not included in this table.