Commitments, Contingencies and Guarantees (Narrative) (Details) - USD ($)	6 Months Ended
	May 31, 2019	Nov. 30, 2018
Commitments Contingencies And Guarantees [Line Items]
Loan commitments outstanding to clients	$ 60,600,000
Fair value of derivative contracts meeting the definition of a guarantee	$ 239,300,000
Standby Letters of Credit
Commitments Contingencies And Guarantees [Line Items]
Expiration period maximum	1 year
Jefferies Finance
Commitments Contingencies And Guarantees [Line Items]
Line of credit facility, commitment of Jefferies, funded	$ 0	$ 0
Line of credit facility commitment of Jefferies	250,000,000.0	$ 250,000,000.0
Berkadia
Commitments Contingencies And Guarantees [Line Items]
Surety policy issued	$ 1,500,000,000
Reimbursement of losses incurred, maximum percentage	50.00%
Aggregate amount of commercial paper outstanding	$ 1,470,000,000
Jefferies Group | Standby Letters of Credit
Commitments Contingencies And Guarantees [Line Items]
Letters of credit	36,900,000
Other subsidiaries | Standby Letters of Credit
Commitments Contingencies And Guarantees [Line Items]
Letters of credit	1,600,000
Jefferies Capital Partners LLC and Its Private Equity Funds
Commitments Contingencies And Guarantees [Line Items]
Equity commitments	17,900,000
Other Investments
Commitments Contingencies And Guarantees [Line Items]
Equity commitments	$ 41,400,000