Commitments, Contingencies and Guarantees - Additional Information (Detail) - USD ($)	12 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2012
Loss Contingencies [Line Items]
Loan commitments outstanding to clients	$ 182,100,000
Future minimum rentals due from non-cancelable sublease	17,600,000
Rent expense, net	56,100,000	$ 57,400,000	$ 57,400,000
Gain on leaseback transaction				$ 2,000,000
Maximum amount payable under guarantee	18,100,000
Fair value of derivative contracts approximated deemed to meet the definition of a guarantee	313,100,000
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Letters of credit commitments	$ 33,300,000
Letters of credit commitments expiration period	2 years
Jefferies Capital Partners LLC [Member]
Loss Contingencies [Line Items]
Outstanding equity commitments	$ 23,100,000
Other Investments [Member]
Loss Contingencies [Line Items]
Outstanding equity commitments	1,600,000
Jefferies Energy Partners I LP [Member] | Private equity vehicles [Member]
Loss Contingencies [Line Items]
Fair value of derivative contracts approximated deemed to meet the definition of a guarantee	$ 3,000,000.0	$ 3,000,000.0