Variable Interest Entities (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended
Feb. 29, 2012	Feb. 28, 2011	Nov. 30, 2011
Variable Interest Entities (Textual) [Abstract]
Additional financial support to securitization of vehicles	$ 0		$ 0
Liabilities related to these securitization of vehicles	0		0
Transferred assets	2,036.8	2,141.7
Net revenues	8.0	8.3
Carrying amount of variable interest as debt, equity and partnership interest	352.8		322.0
Maximum amount committed to make as per agreement	54.0
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Commitment funded	25.2		17.9
Carrying amount of debt securities of variable interest entities	14.0		14.1
Equity investment in Jefferies SBI USA Fund L.P. (the "USA Fund")	75.0
USA Fund [Member]
Variable Interest Entity [Line Items]
Carrying amount of equity investment	18.8		17.4
JEP IV [Member]
Variable Interest Entity [Line Items]
Commitment funded	45.2		44.3
Carrying amount of equity investment	2.8		2.8
Mortgage- and asset-backed vehicles - Agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	1,413.5
Mortgage- and asset-backed vehicles - Non-agency [Member]
Variable Interest Entity [Line Items]
Carrying Amount	$ 466.5

Assets transferred due to securitization activities in which the Company had continuing involvement.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Carrying amount of equity investments.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Carrying amount of variable interest in debt, equity and partnership interests that are eliminated in consolidation.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Commitment funded.

+ References

No definition available.

+ Details

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- Definition

The fair value as of the balance sheet date of firm holdings in collateralized loan obligations in which are Variables Interest Entities.

+ References

No definition available.

+ Details

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- Definition

Maximum amount committed to make as per agreement.

+ References

No definition available.

+ Details

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- Definition

Maximum equity investment.

+ References

No definition available.

+ Details

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- Details

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- Definition

The carrying amount of the listed assets obtained or liabilities incurred.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6865494&loc=d3e99687-111709

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph B11

-Subparagraph b(4)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

A gain (loss) realized on a transfer, accounted for as a sale, of all or a portion of financial assets in which the transferor surrenders control and receives consideration other than a beneficial interest in the assets transferred. Reflects the amount of sales proceeds in excess of, or deficient from, the sum of the carrying amounts of transferred financial assets plus transaction costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph h(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7,9)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

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- Definition

The amount of the support provided by the transferor with a continuing involvement that was not previously contractually required to provide to the transferee or its beneficial interest holders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)(5)(i)

-URI http://asc.fasb.org/extlink&oid=6942082&loc=d3e107314-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4 and FIN46(R)-8

-Paragraph B11

-Subparagraph b

-Clause 1

-Subclause d(i)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Details

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- Definition

The carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph a

-URI http://asc.fasb.org/extlink&oid=6970148&loc=d3e5728-111685

+ Details

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