Derivative Financial Instruments - Fair Value and Related Number of Derivative Contracts Categorized by Type of Derivative Contract (Detail) (USD $) In Thousands, unless otherwise specified	Feb. 28, 2015	Nov. 30, 2014
Derivatives, Fair Value [Line Items]
Net amounts per Consolidated Statements of Financial Condition, Assets	$ 497,092	$ 406,268
Net amounts per Consolidated Statements of Financial Condition, Liabilities	322,341	363,515
Exchange-traded [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	871,000	1,075,642
Fair Value, Liabilities	805,847	1,040,076
Amounts offset in the Consolidated Statements of Financial Condition, Assets	(804,823)	(1,038,992)
Amounts offset in the Consolidated Statements of Financial Condition, Liabilities	(804,823)	(1,038,992)
Cleared OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	1,961,297	1,443,206
Fair Value, Liabilities	1,949,574	1,504,593
Amounts offset in the Consolidated Statements of Financial Condition, Assets	(1,903,362)	(1,416,613)
Amounts offset in the Consolidated Statements of Financial Condition, Liabilities	(1,903,362)	(1,416,613)
Bilateral OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	2,394,328	2,646,765
Fair Value, Liabilities	2,377,671	2,675,464
Amounts offset in the Consolidated Statements of Financial Condition, Assets	(2,021,348)	(2,303,740)
Amounts offset in the Consolidated Statements of Financial Condition, Liabilities	(2,102,566)	(2,401,013)
Interest rate contracts [Member] \| Exchange-traded [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	7,257	2,450
Number of Contracts, Assets	74,982	67,437
Fair Value, Liabilities	3,983	1,400
Number of Contracts, Liabilities	120,525	87,008
Interest rate contracts [Member] \| Cleared OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	1,881,757	1,425,375
Number of Contracts, Assets	2,433	2,160
Fair Value, Liabilities	1,865,499	1,481,329
Number of Contracts, Liabilities	2,482	2,124
Interest rate contracts [Member] \| Bilateral OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	799,302	871,982
Number of Contracts, Assets	1,420	1,908
Fair Value, Liabilities	764,478	809,962
Number of Contracts, Liabilities	1,126	729
Foreign exchange contracts [Member] \| Exchange-traded [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	0	0
Number of Contracts, Assets	587	1,562
Fair Value, Liabilities	0	0
Number of Contracts, Liabilities	302	1,821
Foreign exchange contracts [Member] \| Bilateral OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	1,366,539	1,514,881
Number of Contracts, Assets	13,551	11,299
Fair Value, Liabilities	1,327,400	1,519,349
Number of Contracts, Liabilities	12,565	10,931
Equity contracts [Member] \| Exchange-traded [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	775,242	1,011,101
Number of Contracts, Assets	1,908,334	2,269,044
Fair Value, Liabilities	734,700	987,531
Number of Contracts, Liabilities	1,888,515	2,049,513
Equity contracts [Member] \| Bilateral OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	60,811	39,889
Number of Contracts, Assets	1,528	2,463
Fair Value, Liabilities	103,898	70,484
Number of Contracts, Liabilities	909	1,956
Commodity contracts [Member] \| Exchange-traded [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	88,501	62,091
Number of Contracts, Assets	937,820	1,027,542
Fair Value, Liabilities	67,164	51,145
Number of Contracts, Liabilities	943,863	1,015,894
Commodity contracts [Member] \| Bilateral OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	157,317	214,635
Number of Contracts, Assets	3,411	4,026
Fair Value, Liabilities	148,027	252,061
Number of Contracts, Liabilities	4,259	4,524
Credit contracts [Member] \| Cleared OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	79,540	17,831
Number of Contracts, Assets	102	27
Fair Value, Liabilities	84,075	23,264
Number of Contracts, Liabilities	88	22
Credit contracts [Member] \| Bilateral OTC [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Assets	10,359	5,378
Number of Contracts, Assets	38	18
Fair Value, Liabilities	$ 33,868	$ 23,608
Number of Contracts, Liabilities	42	27

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5579245-113959

+ 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/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226000-175313

+ Details

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

- Definition

Fair value, after effects of master netting arrangements, of 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 offset against an obligation to return collateral. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226016-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

+ 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 effects of master netting arrangements, of 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 offset against the right to receive collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ 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

- 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://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph c

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959

+ 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://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 940

-SubTopic 320

-Section 35

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35711043&loc=d3e42429-110968

+ Details

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

- 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:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_EquityContractMember
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_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
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_InvestmentTypeAxis=jef_OtcClearedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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