Related Party Transactions (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Nov. 30, 2019	Feb. 29, 2020	Feb. 28, 2019
Private Equity Related Funds
Related Party Transaction [Line Items]
Loans to and/or equity investments in related funds	$ 23.0	$ 23.8
JCP Fund V
Related Party Transaction [Line Items]
Net gains (losses) from private equity related funds		1.5	$ (3.2)
Officers and Employees
Related Party Transaction [Line Items]
Loans outstanding to related party	44.8	43.3
Berkadia | Affiliated Entity | Jefferies Group
Related Party Transaction [Line Items]
Purchase commitment	360.4	328.3
Jefferies Finance | Affiliated Entity
Related Party Transaction [Line Items]
Purchases of loan receivables	65.3
Payables, expense accruals and other liabilities | FXCM | Affiliated Entity | Jefferies Group
Related Party Transaction [Line Items]
OTC foreign exchange contracts	$ 9.9	12.7
Financial instruments sold, not yet purchased, at fair value | FXCM | Affiliated Entity | Jefferies Group
Related Party Transaction [Line Items]
OTC foreign exchange contracts		$ 0.7