Commitments, Contingencies and Guarantees - Credit Exposure from Loan Commitments (Footnote) (Detail) (USD $)	Feb. 28, 2015
Commitments and Contingencies Disclosure [Abstract]
Loan Guarantee	$ 0jef_GuaranteeMaximumExposurePayable
Corporate lending exposure included in financial instruments owned	262,000,000
Corporate lending exposure carried at fair value included in financial instruments sold	$ 26,900,000

Corporate lending exposure carried at fair value included in financial instruments owned.

No definition available.

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