Loans to and Investments In Associated Companies (Jefferies LoanCore) (Narrative) (Details) $ in Millions	Oct. 31, 2017 USD ($)
Jefferies LoanCore
Investments In Associated Companies [Line Items]
Equity method investment, ownership percentage	48.50%
Jefferies LoanCore | Disposed of by sale, not discontinued operations | Jefferies Group
Investments In Associated Companies [Line Items]
Consideration for sale of business	$ 173.1
Period entitled to additional cash consideration	5 years