Commitments, Contingencies and Guarantees - Guarantees (Detail) $ in Millions	Aug. 31, 2015 USD ($)
Guarantee Obligations [Line Items]
Notional/ Maximum Payout	$ 6,487.4
Derivative contracts - non-credit related [Member]
Guarantee Obligations [Line Items]
2015	19,399.8
2016	4,076.5
2017 and 2018	382.4
2019 and 2020	250.0
2021 and Later	440.0
Notional/ Maximum Payout	24,548.7
Written derivative contracts - credit related [Member]
Guarantee Obligations [Line Items]
2015	0.0
2016	0.0
2017 and 2018	50.6
2019 and 2020	1,904.9
2021 and Later	20.0
Notional/ Maximum Payout	1,975.5
Derivatives [Member]
Guarantee Obligations [Line Items]
2015	19,399.8
2016	4,076.5
2017 and 2018	433.0
2019 and 2020	2,154.9
2021 and Later	460.0
Notional/ Maximum Payout	$ 26,524.2

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

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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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

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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

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Data Type:	xbrli:monetaryItemType
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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

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Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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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 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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- Details

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- Details

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- Details

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