Acquisition of the Global Commodities Group (Details) (USD $) In Thousands	3 Months Ended	9 Months Ended
	Aug. 31, 2011	Aug. 31, 2011	Jul. 01, 2011
Assets acquired:
Cash and cash equivalents			$ 101,343
Cash and securities segregated			3,130,586
Financial instruments owned, at fair value			918,598
Securities purchased under agreements to resell			1,489
Receivables:
Brokers, dealers and clearing organizations			313,939
Customers			173,477
Fees, interest and other			122
Premises and equipment			13,584
Indefinite-lived intangible exchange memberships and licenses			11,219
Other assets			32,076
Total assets			4,703,533
Liabilities assumed:
Short-term borrowings			301,027
Financial instruments sold, not yet purchased, at fair value			267,200
Payables:
Brokers, dealers and clearing organizations			43,588
Customers			3,384,263
Accrued expenses and other liabilities			232,933
Total liabilities			4,229,011
Fair value of net assets acquired	474,500	474,500	474,522
Purchase price:
Cash			422,013
Total purchase price	422,000	422,000	422,013
Bargain purchase gain	52,509	52,509
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible customer relationships			5,800
Trade names (intangible assets) [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible customer relationships			$ 1,300