Securitization Activities - Additional Information (Details) - USD ($)	Feb. 28, 2018	Nov. 30, 2017
Transfers and Servicing [Abstract]
Carrying value of assets resulting from transfers	$ 4,000,000	$ 0
Carrying value of liabilities resulting from transfers	$ 3,900,000	$ 0

Carrying Value Of Liabilities Resulting From Transfers

No definition available.

Name:	jef_CarryingValueOfLiabilitiesResultingFromTransfers
Namespace Prefix:	jef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant