Investments - Summary of Selected Financial Information for Jefferies Finance (Details) - Jefferies Finance, LLC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2019	Aug. 31, 2018	Nov. 30, 2018
Schedule of Equity Method Investments [Line Items]
Interest income	$ 0.0	$ 0.0	$ 0.0	$ 1.2
Unfunded commitment fees	0.3	0.3	0.9	0.8
Our total equity balance	635.5		635.5		$ 694.8
Net earnings (loss)	(16.3)	38.0	31.5	140.7
Origination and syndication fee revenues	44.6	71.1	135.8	282.1
Origination fee expenses	8.2	12.1	21.8	45.5
CLO placement fee revenues	1.0	0.4	2.3	3.1
Derivative losses	0.0	(0.3)	0.0	(0.9)
Underwriting fees	2.9	0.0	3.9	0.3
Service fees	$ 12.3	$ 13.3	$ 50.6	$ 48.3