Consideration For Release of Indemnity Relating To Pension Obligations

No definition available.

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

- Definition

Defined Benefit Plan, Payment To Transfer Defined Benefit Obligation And Insurance Contracts

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow from a borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromShortTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow for a borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfShortTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_AdjustmentsForChangeInAccountingPrincipleAxis=jef_ChangesToPresentationOfConsolidatedStatementsOfCashFlowsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=jef_ThreePointEightSevenFivePercentageConvertibleSeniorDebenturesDueTwoThousandTwentyNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanSponsorLocationAxis=us-gaap_ForeignPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=jef_JefferiesBacheLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Organization and Basis of Presentation (Detail) € in Millions	6 Months Ended
	May 31, 2018 USD ($) segment	May 31, 2017 USD ($)	Dec. 28, 2017 EUR (€)	Dec. 28, 2017 USD ($)
Debt Instrument [Line Items]
Number of operating segments \| segment	2
Proceeds from short-term borrowings	$ 372,481,000	$ 133,928,000
Payments on short-term borrowings	$ 297,708,000	219,086,000
Changes to presentation of Consolidated Statements of Cash Flows
Debt Instrument [Line Items]
Proceeds from short-term borrowings		(16,753,500,000)
Payments on short-term borrowings		$ 16,753,500,000
3.875% Convertible Senior Debentures
Debt Instrument [Line Items]
Debt instrument interest rate	3.875%
Debt principal amount	$ 345,000,000.0
German Plan \| Pension Plan
Debt Instrument [Line Items]
Consideration for release of indemnity relating to pension obligations				$ 3,250,000
German Plan \| Pension Plan \| Jefferies Bache Limited
Debt Instrument [Line Items]
Payment to transfer defined benefit obligation and insurance contracts \| €			€ 6.5