Line items represent reporting 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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Sentence Column A

+ Details

Name:	invest_InvestmentLineItems
Namespace Prefix:	invest_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash Invested In Limited Liability Company

+ References

No definition available.

+ Details

Name:	jef_CashInvestedInLimitedLiabilityCompany
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Contributions from Noncontrolling Interests

+ References

No definition available.

+ Details

Name:	jef_ContributionsfromNoncontrollingInterests
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Ownership Percentage

+ References

No definition available.

+ Details

Name:	jef_OwnershipPercentage
Namespace Prefix:	jef_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Prior Ownership Percentage

+ References

No definition available.

+ Details

Name:	jef_PriorOwnershipPercentage
Namespace Prefix:	jef_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ 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 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 35
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=114001220&loc=d3e32787-111569

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Details

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

- Details

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

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=jef_InvestmentInGoldenQueenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=jef_GaussLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans to and Investments in Associated Companies - Golden Queen Mining Company (Details) - USD ($) $ in Millions	3 Months Ended	11 Months Ended	71 Months Ended
	Sep. 30, 2018	Nov. 30, 2018	Nov. 30, 2019	Dec. 31, 2013
Investment [Line Items]
Cash invested in Limited Liability Company			$ 93.0
Golden Queen
Investment [Line Items]
Equity method investment, ownership percentage			50.00%
Golden Queen Mining Co, Ltd
Investment [Line Items]
Prior ownership percentage				100.00%
Ownership percentage			50.00%
Clay Family
Investment [Line Items]
Contributions from noncontrolling interests			$ 34.5
Investment In Golden Queen
Investment [Line Items]
Equity method investment impairment	$ 47.9	$ 47.9
Gauss LLC \| Golden Queen
Investment [Line Items]
Total investment in associated company			$ 127.5