Commitments, Contingencies and Guarantees - Additional Information (Detail) $ in Millions	3 Months Ended
	Feb. 28, 2018 USD ($)
Loss Contingencies [Line Items]
Loan commitments outstanding to clients	$ 66.8
Fair value of mortgage-related commitments	1.1
Fair value of derivative contracts approximated deemed to meet the definition of a guarantee	391.4
Standby Letters of Credit
Loss Contingencies [Line Items]
Letters of credit commitments	52.0
Jefferies Capital Partners LLC
Loss Contingencies [Line Items]
Outstanding equity commitments	21.8
Other Investments
Loss Contingencies [Line Items]
Outstanding equity commitments	$ 1.0
Maximum | Standby Letters of Credit
Loss Contingencies [Line Items]
Standby letters of credit expiration period	1 year