Commitments, Contingencies and Guarantees - Credit Exposure from Loan Commitments (Footnote) (Detail)	May. 31, 2015 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Loan guarantee	$ 0
Corporate lending exposure included in financial instruments owned	215,300,000
Corporate lending exposure carried at fair value included in financial instruments sold	$ 21,300,000

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