Commitments, Contingencies and Guarantees - Additional Information (Detail) $ in Millions	6 Months Ended
	May 31, 2019 USD ($)
Loss Contingencies [Line Items]
Loan commitments outstanding to clients	$ 60.6
Fair value of derivative contracts approximated deemed to meet the definition of a guarantee	239.3
Standby Letters of Credit
Loss Contingencies [Line Items]
Letters of credit commitments	36.9
Jefferies Capital Partners LLC
Loss Contingencies [Line Items]
Outstanding equity commitments	17.9
Other Investments
Loss Contingencies [Line Items]
Outstanding equity commitments	$ 13.5
Maximum | Standby Letters of Credit
Loss Contingencies [Line Items]
Standby letters of credit expiration period	1 year