Commitments, Contingencies and Guarantees - Additional Information (Detail) - USD ($)	3 Months Ended
	Feb. 28, 2017	Nov. 30, 2016
Loss Contingencies [Line Items]
Loan commitments outstanding to clients	$ 177,500,000
Fair value of mortgage-related commitments	14,400,000
Fair value of derivative contracts approximated deemed to meet the definition of a guarantee	134,100,000
Maximum amount payable under guarantee	17,800,000
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Letters of credit commitments	$ 63,200,000
Standby letters of credit expiration period	1 year
Jefferies Capital Partners LLC [Member]
Loss Contingencies [Line Items]
Outstanding equity commitments	$ 22,800,000
Other Investments [Member]
Loss Contingencies [Line Items]
Outstanding equity commitments	1,600,000
Related party private equity vehicles [Member] | Jefferies Energy Partners I LP [Member]
Loss Contingencies [Line Items]
Fair value of derivative contracts approximated deemed to meet the definition of a guarantee	$ 3,000,000	$ 3,000,000.0