Commitments, Contingencies and Guarantees - Guarantees (Detail) (USD $) In Millions, unless otherwise specified	Feb. 28, 2013
Guarantee Obligations [Line Items]
Notional/ Maximum Payout	$ 4,045.1
Derivative contracts - non-credit related [Member]
Guarantee Obligations [Line Items]
2013	11,620.4
2014	353.7
2015 and 2016	9.9
2017 and 2018
2019 and Later
Notional/ Maximum Payout	11,984.0
Written derivative contracts - credit related [Member]
Guarantee Obligations [Line Items]
2013
2014
2015 and 2016
2017 and 2018	789.5
2019 and Later
Notional/ Maximum Payout	789.5
Derivatives [Member]
Guarantee Obligations [Line Items]
2013	11,620.4
2014	353.7
2015 and 2016	9.9
2017 and 2018	789.5
2019 and Later
Notional/ Maximum Payout	$ 12,773.5

Guarantees with a remaining term that matures during the fiscal year. These may include derivative guarantees, etc.

No definition available.

Name:	jef_GuaranteesExpectedToBeDueCurrent
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Guarantees expected to be due within 5 to 6 fiscal years. These may include, derivative guarantees, etc.

+ References

No definition available.

+ Details

Name:	jef_GuaranteesExpectedToBeDueInFiveAndSixYears
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Guarantees expected to be due within 3 to 4 fiscal years. These may include, derivative guarantees, etc.

+ References

No definition available.

+ Details

Name:	jef_GuaranteesExpectedToBeDueInThreeAndFourYears
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Guarantees expected to be due within 2 fiscal years. These may include, derivative guarantees, etc.

+ References

No definition available.

+ Details

Name:	jef_GuaranteesExpectedToBeDueInTwoYears
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Guarantees expected to be due within 7 fiscal years and thereafter. These may include, derivative guarantees, etc

+ References

No definition available.

+ Details

Name:	jef_GuaranteesExpectedToBeDueThereafter
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_GuaranteeObligationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph b

-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 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant