Investments - Summary of Selected Financial Information for Jefferies Finance (Details) - Jefferies Finance - USD ($) $ in Millions	12 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2017
Schedule of Equity Method Investments [Line Items]
Interest income	$ 0.0	$ 1.2	$ 2.9
Unfunded commitment fees	1.3	1.2	1.0
Total assets	7,112.4	7,776.5
Total liabilities	5,828.3	6,386.9
Total equity	1,284.1	1,389.6
Our total equity balance	642.0	694.8
Net earnings	44.5	197.2	181.7
Origination and syndication fee revenues	176.3	377.7	327.9
Origination fee expenses	27.6	56.6	2.4
CLO placement fee revenues	6.0	3.7	6.1
Derivative gains (losses)	0.0	(1.6)	(1.1)
Underwriting fees	3.9	0.3	0.0
Service fees	$ 60.8	$ 61.7	$ 50.7