Commitments, Contingencies and Guarantees - Additional Information (Detail) $ in Millions	3 Months Ended
	Feb. 28, 2019 USD ($)
Loss Contingencies [Line Items]
Loan commitments outstanding to clients	$ 584.0
Fair value of derivative contracts approximated deemed to meet the definition of a guarantee	161.7
Standby Letters of Credit
Loss Contingencies [Line Items]
Letters of credit commitments	37.1
Jefferies Capital Partners LLC
Loss Contingencies [Line Items]
Outstanding equity commitments	17.9
Other Investments
Loss Contingencies [Line Items]
Outstanding equity commitments	$ 3.3
Maximum | Standby Letters of Credit
Loss Contingencies [Line Items]
Standby letters of credit expiration period	1 year