Fair Value Disclosures - Investments Measured at Fair Value Based on Net Asset Value Per Share (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
May 31, 2025	Nov. 30, 2024
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 1,440,253	$ 1,252,689
Unfunded Commitments	191,726	293,780
Hedge Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	689,960	660,720
Unfunded Commitments	$ 0	$ 0
Hedge Funds \| Debt Instrument, Redemption, Period One
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of redeemable investments		53.00%
Hedge Funds \| Debt Instrument, Redemption, Period One \| 90 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of redeemable investments	50.00%
Notice period redemption of investment prior written notice period	90 days	90 days
Hedge Funds \| Debt Instrument, Redemption, Period One \| 45 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investment prior written notice period	45 days	45 days
Hedge Funds \| Debt Instrument, Redemption, Period Two
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of redeemable investments		47.00%
Hedge Funds \| Debt Instrument, Redemption, Period Two \| 60 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of redeemable investments	50.00%
Notice period redemption of investment prior written notice period	60 days	60 days
Hedge Funds \| Debt Instrument, Redemption, Period Two \| 45 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investment prior written notice period	45 days	45 days
Private Equity Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 64,532	$ 60,215
Unfunded Commitments	$ 26,638	$ 30,530
Percentage of not redeemable investments	100.00%	100.00%
Estimated period for the liquidation of the underlying assets, minimum	1 year	1 year
Expected period for the liquidation of the underlying assets, maximum	10 years	10 years
Credit Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 489,597	$ 430,429
Unfunded Commitments	$ 106	$ 30,554
Percentage of not redeemable investments	38.00%	25.00%
Credit Funds \| Debt Instrument, Redemption, Period One \| 90 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of redeemable investments	60.00%	72.00%
Notice period redemption of investment prior written notice period	90 days	90 days
Credit Funds \| Debt Instrument, Redemption, Period Two \| 30 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of redeemable investments	2.00%	3.00%
Notice period redemption of investment prior written notice period	30 days	30 days
Real Estate and Other Funds
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 196,164	$ 101,325
Unfunded Commitments	$ 164,982	$ 232,696
Percentage of not redeemable investments	74.00%	100.00%
Real Estate and Other Funds \| 90 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of redeemable investments	26.00%
Notice period redemption of investment prior written notice period	90 days
Short-term Investments \| 90 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investment prior written notice period	90 days	90 days
Short-term Investments \| 120 Days Prior Written Notice
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investment prior written notice period	120 days	120 days

Expected Period For Liquidation Of Underlying Assets Maximum

No definition available.

Name:	jef_ExpectedPeriodForLiquidationOfUnderlyingAssetsMaximum
Namespace Prefix:	jef_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Expected Period For Liquidation Of Underlying Assets Minimum

+ References

No definition available.

+ Details

Name:	jef_ExpectedPeriodForLiquidationOfUnderlyingAssetsMinimum
Namespace Prefix:	jef_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Not Redeemable Investments

+ References

No definition available.

+ Details

Name:	jef_NotRedeemableInvestments
Namespace Prefix:	jef_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Investments at fair value that cannot be redeemed at reporting date and are subject to a prior written redemption request.

+ References

No definition available.

+ Details

Name:	jef_NoticePeriodRedemptionOfInvestmentsPriorWrittenNoticePeriod
Namespace Prefix:	jef_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Investments redeemable within 60-90 days

+ References

No definition available.

+ Details

Name:	jef_RedeemableInvestments
Namespace Prefix:	jef_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value of investment other than investment in equity security, investment in debt security and equity method investment. Includes, but is not limited to, investment in certain entities that calculate net asset value per share. Example includes, but is not limited to, investment in hedge fund, venture capital fund, private equity fund, and real estate partnership or fund.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-28

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-11

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-11

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 103
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-103

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 54B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482134/820-10-35-54B

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

+ Details

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

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 54B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482134/820-10-35-54B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

+ Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jef_InvestmentRedemptionPriorWrittenNoticePeriodAxis=jef_A90DaysPriorWrittenNoticeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jef_InvestmentRedemptionPriorWrittenNoticePeriodAxis=jef_A45DaysPriorWrittenNoticeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	jef_InvestmentRedemptionPriorWrittenNoticePeriodAxis=jef_A60DaysPriorWrittenNoticeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	jef_InvestmentRedemptionPriorWrittenNoticePeriodAxis=jef_A30DaysPriorWrittenNoticeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	jef_InvestmentRedemptionPriorWrittenNoticePeriodAxis=jef_A120DaysPriorWrittenNoticeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: