Variable Interest Entities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended						3 Months Ended
	Feb. 28, 2013	Nov. 30, 2012	Feb. 28, 2013 Variable Interest Entity Not Primary Beneficiary [Member]	Nov. 30, 2012 Variable Interest Entity Not Primary Beneficiary [Member]	Feb. 28, 2013 USA Fund [Member]	Nov. 30, 2012 USA Fund [Member]	Feb. 28, 2013 JEP IV [Member]	Nov. 30, 2012 JEP IV [Member]	Feb. 28, 2013 High Yield [Member]	Nov. 30, 2012 High Yield [Member]	Feb. 28, 2013 Collateralized loan obligations securitizations [Member] Variable Interest Entity Not Primary Beneficiary [Member]		Nov. 30, 2012 Collateralized loan obligations securitizations [Member] Variable Interest Entity Not Primary Beneficiary [Member]		Feb. 28, 2013 Agency mortgage- and asset-backed securitizations [Member]	Feb. 28, 2013 Agency mortgage- and asset-backed securitizations [Member] Variable Interest Entity Not Primary Beneficiary [Member]		Nov. 30, 2012 Agency mortgage- and asset-backed securitizations [Member] Variable Interest Entity Not Primary Beneficiary [Member]		Feb. 28, 2013 Non-agency mortgage- and asset-backed securitizations [Member]	Feb. 28, 2013 Non-agency mortgage- and asset-backed securitizations [Member] Variable Interest Entity Not Primary Beneficiary [Member]		Nov. 30, 2012 Non-agency mortgage- and asset-backed securitizations [Member] Variable Interest Entity Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Carrying amount of variable interest as debt, equity and partnership interest									$ 409.2	$ 389.4
Additional financial support to securitization of vehicles	0	0
Liabilities related to these securitization of vehicles	0	0
Fair value of debt securities of variable interests entities											4.8		5.3
Carrying Amount			2,319.7	2,456.5							24.5	[1]	5.3	[1]	1,300.4	1,300.4	[1],[2]	1,579.1	[1],[3]	938.1	938.1	[1],[2]	814.1	[1],[3]
Collateralized loan obligations	24.5
Equity investment in Jefferies SBI USA Fund L.P. (the "USA Fund")						75.0
Commitment funded					36.8	27.1	28.2	32.7
Carrying amount of equity investment					24.0	20.8	1.6	1.5
Maximum amount committed to make as per agreement							$ 33.0

[1] Consists of debt securities accounted for at fair value, which are included within Financial instruments owned.

[2] VIE assets represent the unpaid principal balance of the assets in these vehicles at February 28, 2013 and represent the underlying assets that provide the cash flows supporting our variable interests.

[3] VIE assets represent the unpaid principal balance of the assets in these vehicles at November 30, 2012 and represent the underlying assets that provide the cash flows supporting our variable interests.