Variable Interest Entities - Variable Interests in Non-Consolidated Variable Interest Entities (Detail) - Nonconsolidated VIEs - USD ($) $ in Millions	Nov. 30, 2017	Nov. 30, 2016
Variable Interest Entity [Line Items]
Carrying Amount, Assets	$ 490.0	$ 443.5
Carrying Amount, Liabilities	8.9	4.8
Maximum exposure to loss	1,874.4	1,257.0
VIE Assets	10,546.5	9,467.5
CLOs
Variable Interest Entity [Line Items]
Carrying Amount, Assets	163.5	263.3
Carrying Amount, Liabilities	8.9	4.8
Maximum exposure to loss	1,020.5	920.0
VIE Assets	5,210.4	4,451.7
Consumer loan vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	254.8	90.3
Carrying Amount, Liabilities	0.0	0.0
Maximum exposure to loss	759.8	219.6
VIE Assets	2,322.7	985.5
Related party private equity vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	23.7	37.6
Carrying Amount, Liabilities	0.0	0.0
Maximum exposure to loss	45.4	63.6
VIE Assets	75.0	155.6
Other private investment vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	48.0	52.3
Carrying Amount, Liabilities	0.0	0.0
Maximum exposure to loss	48.7	53.8
VIE Assets	$ 2,938.4	$ 3,874.7

Variable Interest Entity Carrying Amount Of Assets Non Consolidated Vie

No definition available.

Name:	jef_VariableInterestEntityCarryingAmountOfAssetsNonConsolidatedVie
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with 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 b
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5747-111685

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
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

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), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

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Period Type:	instant

- Definition

Carrying amount of the liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

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- Details

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- Details

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- Details

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