Variable Interest Entities (Details) (USD $)	Feb. 29, 2012	Nov. 30, 2011	Feb. 28, 2011	Nov. 30, 2010
Assets and liabilities of consolidated VIEs prior to consolidation
Cash and cash equivalents	$ 2,589,193,000	$ 2,393,797,000	$ 1,164,333,000	$ 2,188,998,000
Total financial instruments owned, at fair value	14,100,548,000	16,678,541,000
Securities borrowed	5,036,447,000	5,169,689,000
Brokers, dealers and clearing organizations	1,720,976,000	1,235,393,000
Other assets	820,070,000	748,072,000
Total assets	34,563,740,000	34,971,422,000
Total financial instruments sold, not yet purchased, at fair value	8,001,713,000	6,604,973,000
Brokers, dealers and clearing organizations	1,316,673,000	2,816,877,000
Mandatorily redeemable preferred interest of consolidated subsidiaries	332,378,000	310,534,000
Total liabilities	30,943,819,000	31,434,447,000
Variable Interest Entities (Textual) [Abstract]
Carrying amount of mandatorily redeemable preferred interest of consolidated subsidiaries	332,378,000	310,534,000
Carrying amount of variable interest as debt, equity and partnership interest	352,800,000	322,000,000
Variable Interest Entity, Primary Beneficiary
Assets and liabilities of consolidated VIEs prior to consolidation
Cash and cash equivalents	455,673,000	345,959,000
Total financial instruments owned, at fair value	654,016,000	712,778,000
Brokers, dealers and clearing organizations	82,452,000	150,592,000
Other assets	304,000	385,000
Total assets	1,198,294,000	1,217,110,000
Total financial instruments sold, not yet purchased, at fair value	352,862,000	326,238,000
Brokers, dealers and clearing organizations	79,587,000	105,165,000
Mandatorily redeemable preferred interest of consolidated subsidiaries	332,378,000	310,534,000
Total liabilities	776,203,000	751,677,000
Variable Interest Entities (Textual) [Abstract]
Carrying amount of mandatorily redeemable preferred interest of consolidated subsidiaries	332,378,000	310,534,000
Secured financing included in inventory and eliminated	9,200,000	8,400,000
High Yield [Member] | Variable Interest Entity, Primary Beneficiary
Assets and liabilities of consolidated VIEs prior to consolidation
Cash and cash equivalents	455,400,000	345,700,000
Total financial instruments owned, at fair value	635,400,000	693,300,000
Securities borrowed	290,300,000	195,300,000
Brokers, dealers and clearing organizations	82,500,000	150,600,000
Other assets	6,800,000	8,500,000
Total assets	1,470,400,000	1,393,400,000
Total financial instruments sold, not yet purchased, at fair value	352,900,000	326,200,000
Brokers, dealers and clearing organizations	79,600,000	105,200,000
Mandatorily redeemable preferred interest of consolidated subsidiaries	1,016,200,000	943,400,000
Other	23,800,000	20,700,000
Total liabilities	1,472,500,000	1,395,500,000
Variable Interest Entities (Textual) [Abstract]
Carrying amount of mandatorily redeemable preferred interest of consolidated subsidiaries	1,016,200,000	943,400,000
Mortgage and Asset-backed Securitizations [Member] | Variable Interest Entity, Primary Beneficiary
Assets and liabilities of consolidated VIEs prior to consolidation
Cash and cash equivalents		0
Total financial instruments owned, at fair value	12,000,000	12,200,000
Total assets	12,000,000	12,200,000
Secured financing	12,000,000	12,200,000
Total liabilities	12,000,000	12,200,000
Other [Member] | Variable Interest Entity, Primary Beneficiary
Assets and liabilities of consolidated VIEs prior to consolidation
Cash and cash equivalents	300,000	300,000
Total financial instruments owned, at fair value	6,600,000	7,200,000
Total assets	6,900,000	7,500,000
Promissory note	4,200,000	4,200,000
Other	200,000
Total liabilities	$ 4,400,000	$ 4,400,000