Investments - Summary of Selected Financial Information for Jefferies Finance (Detail) - Jefferies Finance, LLC [Member] - USD ($) $ in Millions	Aug. 31, 2015	Nov. 30, 2014
Schedule of Equity Method Investments [Line Items]
Total assets	$ 7,037.1	$ 5,954.0
Total liabilities	6,016.3	4,961.7
Total equity	1,020.8	992.3
Our total equity balance	$ 510.4	$ 496.0