Net Capital Requirements (Details) - Jefferies LLC $ in Millions	Dec. 31, 2017 USD ($)
Net Capital Requirements [Line Items]
Net Capital	$ 1,418.9
Excess Net Capital	$ 1,330.2

Net capital is equal to the net worth of the broker dealer, less certain items such as exchange memberships, carrying value of securities not readily marketable, haircuts on marketable securities in proprietary accounts, furniture and equipment and other illiquid assets as defined.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

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