Derivative Financial Instruments - Fair Value and Related Number of Derivative Contracts Categorized by Type of Derivative Contract (Details) $ in Thousands	Feb. 29, 2024 USD ($) Contract	Nov. 30, 2023 USD ($) Contract
Derivatives, Fair Value [Line Items]
Net amounts per consolidated statements of financial condition, assets	$ 692,046	$ 550,844
Net amounts per consolidated statements of financial condition, liabilities	1,226,053	1,145,777
Exchange-traded
Derivatives, Fair Value [Line Items]
Fair value, assets	854,984	678,917
Fair value, liabilities	478,550	393,316
Amounts offset in the consolidated statements of financial condition, assets	(460,355)	(384,392)
Amounts offset in the consolidated statements of financial condition, liabilities	(460,355)	(384,392)
Cleared OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	266,936	1,194,983
Fair value, liabilities	264,219	1,230,060
Amounts offset in the consolidated statements of financial condition, assets	(258,600)	(1,189,517)
Amounts offset in the consolidated statements of financial condition, liabilities	(264,050)	(1,189,513)
Bilateral OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	1,783,709	1,784,564
Fair value, liabilities	2,450,567	2,286,973
Amounts offset in the consolidated statements of financial condition, assets	(1,494,628)	(1,533,711)
Amounts offset in the consolidated statements of financial condition, liabilities	(1,242,878)	(1,190,667)
Derivatives designated as accounting hedges
Derivatives, Fair Value [Line Items]
Fair value, assets	1,456	259
Fair value, liabilities	18,132	25,708
Derivatives designated as accounting hedges \| Interest rate contracts \| Cleared OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 832	$ 0
Number of contracts, assets \| Contract	3	0
Fair value, liabilities	$ 0	$ 6,070
Number of contracts, liabilities \| Contract	0	3
Derivatives designated as accounting hedges \| Foreign exchange contracts \| Bilateral OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 624	$ 259
Number of contracts, assets \| Contract	1	1
Fair value, liabilities	$ 18,132	$ 19,638
Number of contracts, liabilities \| Contract	3	3
Derivatives not designated as accounting hedges
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 2,904,173	$ 3,658,205
Fair value, liabilities	3,175,204	3,884,641
Derivatives not designated as accounting hedges \| Interest rate contracts \| Exchange-traded
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 315	$ 316
Number of contracts, assets \| Contract	43,935	88,354
Fair value, liabilities	$ 404	$ 63
Number of contracts, liabilities \| Contract	43,259	67,643
Derivatives not designated as accounting hedges \| Interest rate contracts \| Cleared OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 231,212	$ 1,156,937
Number of contracts, assets \| Contract	5,081	4,415
Fair value, liabilities	$ 223,877	$ 1,185,503
Number of contracts, liabilities \| Contract	4,902	4,544
Derivatives not designated as accounting hedges \| Interest rate contracts \| Bilateral OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 720,132	$ 893,983
Number of contracts, assets \| Contract	728	1,179
Fair value, liabilities	$ 1,106,992	$ 1,266,506
Number of contracts, liabilities \| Contract	1,368	786
Derivatives not designated as accounting hedges \| Foreign exchange contracts \| Exchange-traded
Derivatives, Fair Value [Line Items]
Fair value, assets		$ 0
Number of contracts, assets \| Contract		0
Fair value, liabilities		$ 0
Number of contracts, liabilities \| Contract		4
Derivatives not designated as accounting hedges \| Foreign exchange contracts \| Bilateral OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 119,871	$ 147,470
Number of contracts, assets \| Contract	64,160	66,254
Fair value, liabilities	$ 103,604	$ 129,770
Number of contracts, liabilities \| Contract	39,104	38,585
Derivatives not designated as accounting hedges \| Equity contracts \| Exchange-traded
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 854,640	$ 678,542
Number of contracts, assets \| Contract	890,720	1,180,832
Fair value, liabilities	$ 478,145	$ 393,220
Number of contracts, liabilities \| Contract	884,169	1,174,298
Derivatives not designated as accounting hedges \| Equity contracts \| Bilateral OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 905,684	$ 715,754
Number of contracts, assets \| Contract	34,477	31,116
Fair value, liabilities	$ 1,192,065	$ 850,088
Number of contracts, liabilities \| Contract	16,945	16,234
Derivatives not designated as accounting hedges \| Commodity contracts \| Exchange-traded
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 29	$ 59
Number of contracts, assets \| Contract	656	735
Fair value, liabilities	$ 1	$ 33
Number of contracts, liabilities \| Contract	744	940
Derivatives not designated as accounting hedges \| Commodity contracts \| Bilateral OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 3,271	$ 5,662
Number of contracts, assets \| Contract	13,288	15,497
Fair value, liabilities	$ 885	$ 1,398
Number of contracts, liabilities \| Contract	6,472	6,455
Derivatives not designated as accounting hedges \| Credit contracts \| Cleared OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 34,892	$ 38,046
Number of contracts, assets \| Contract	107	133
Fair value, liabilities	$ 40,342	$ 38,487
Number of contracts, liabilities \| Contract	76	81
Derivatives not designated as accounting hedges \| Credit contracts \| Bilateral OTC
Derivatives, Fair Value [Line Items]
Fair value, assets	$ 34,127	$ 21,436
Number of contracts, assets \| Contract	21	22
Fair value, liabilities	$ 28,889	$ 19,573
Number of contracts, liabilities \| Contract	36	29

The number of derivative instruments of a particular derivative asset or group of derivative assets held by the entity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

+ Details

Name:	us-gaap_DerivativeAssetNumberOfInstrumentsHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483444/210-20-55-22

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483466/210-20-50-3

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483444/210-20-55-7

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-SubTopic 20
-Topic 860
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481326/860-20-50-4D

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, after effect of master netting arrangement and deduction of obligation to return financial collateral not offset and financial instrument subject to master netting arrangement not offset, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and contract can be net settled by means outside contract or delivery of asset. Includes derivative not subject to master netting arrangement or similar agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 13
-SubTopic 20
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483444/210-20-55-13

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-8

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

+ Details

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

- Definition

Fair value, after effect of master netting arrangement and deduction of obligation to return financial collateral not offset and financial instrument subject to master netting arrangement not offset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and contract can be net settled by means outside contract or delivery of asset. Includes derivative not subject to master netting arrangement or similar agreement.

+ References

+ Details

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

- Definition

The number of derivative instruments of a particular derivative liability or group of derivative liabilities held by the entity.

+ References

+ Details

Name:	us-gaap_DerivativeLiabilityNumberOfInstrumentsHeld
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
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_DerivativesFairValueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The fair value as of the balance sheet date of firm holdings in all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments. Their value is derived from the values of one or more underlying assets, reference rates, or indices of asset values. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4B
-Subparagraph c
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B

+ Details

Name:	us-gaap_FinancialInstrumentsOwnedDerivativesAndOtherContractualAgreementsAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of obligations arising from derivatives and other contracts sold short.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 35
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481992/940-320-35-1

+ Details

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

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ExchangeTradedOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=jef_OtcClearedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=jef_BilateralOtcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_EquityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CreditRiskContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: