Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016
Statement of Comprehensive Income [Abstract]
Changes in instrument specific credit risk, tax benefit	$ 1.1	$ 1.5	$ 7.4	$ 1.5

Other Comprehensive Income (Loss), Changes in Instrument Specific Credit Risk, Tax

No definition available.

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