Variable Interest Entities - Variable Interests in Non-Consolidated Variable Interest Entities (Detail) - Variable Interest Entity Not Primary Beneficiary [Member] - USD ($) $ in Millions	Aug. 31, 2016	Nov. 30, 2015
Variable Interest Entity [Line Items]
Carrying Amount, Assets	$ 339.0	$ 352.5
Carrying Amount, Liabilities	7.6	0.2
Maximum exposure to loss in non-consolidated VIEs	1,057.0	1,422.5
VIE Assets	10,245.7	11,981.9
Collateralized loan obligations [Member]
Variable Interest Entity [Line Items]
Carrying Amount, Assets	73.3	73.6
Carrying Amount, Liabilities	7.6	0.2
Maximum exposure to loss in non-consolidated VIEs	326.7	458.1
VIE Assets	4,879.1	6,368.7
Consumer Loan Vehicles [Member]
Variable Interest Entity [Line Items]
Carrying Amount, Assets	170.0	188.3
Carrying Amount, Liabilities	0.0	0.0
Maximum exposure to loss in non-consolidated VIEs	607.2	845.8
VIE Assets	1,231.4	1,133.0
Related party private equity vehicles [Member]
Variable Interest Entity [Line Items]
Carrying Amount, Assets	38.3	39.3
Carrying Amount, Liabilities	0.0	0.0
Maximum exposure to loss in non-consolidated VIEs	64.2	65.8
VIE Assets	157.5	168.2
Other private investment vehicles [Member]
Variable Interest Entity [Line Items]
Carrying Amount, Assets	57.4	51.3
Carrying Amount, Liabilities	0.0	0.0
Maximum exposure to loss in non-consolidated VIEs	58.9	52.8
VIE Assets	$ 3,977.7	$ 4,312.0

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

Name:	us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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

Name:	us-gaap_VariableInterestEntityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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

Name:	us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

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

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CollateralizedLoanObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=jef_ConsumerLoanFinancingVehiclesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=jef_PrivateEquityVehiclesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=jef_OtherPrivateInvestmentVehiclesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: