Loans to and Investments In Associated Companies (Jefferies Finance) (Narrative) (Details) - USD ($)	3 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Nov. 30, 2019
Investments In Associated Companies [Line Items]
Other	$ 2,654,158,000		$ 2,450,109,000
Financial instruments sold, not yet purchased, at fair value	9,879,387,000		10,532,460,000
Payables, expense accruals and other liabilities	9,447,230,000		8,179,013,000
Financial instruments owned, at fair value (including securities pledged of $13,446,620 and $12,058,522):	18,396,981,000		16,895,741,000
Jefferies Finance
Investments In Associated Companies [Line Items]
Equity commitment	750,000,000.0
Funded equity commitments	$ 652,400,000
Investment commitment extension	1 year
Investment Commitment Termination Notice Period	60 days
Total line of credit facility commitment under joint venture	$ 500,000,000.0
Termination notice	60 days
Line of credit facility, commitment of Jefferies, funded	$ 0
Line of credit facility commitment of Jefferies	$ 250,000,000.0
Jefferies Finance
Investments In Associated Companies [Line Items]
Equity method investment, ownership percentage	50.00%
Extension period	1 year
Other	$ 18,300,000		17,200,000
Payables, expense accruals and other liabilities	22,200,000		31,300,000
Jefferies Finance | Jefferies Group
Investments In Associated Companies [Line Items]
Interest income and unfunded commitment fees related to facility commitment	1,100,000	$ 300,000
Foreign exchange contracts: | Jefferies Finance
Investments In Associated Companies [Line Items]
Financial instruments sold, not yet purchased, at fair value			200,000
Payables, expense accruals and other liabilities			$ 4,700,000
Financial instruments owned, at fair value (including securities pledged of $13,446,620 and $12,058,522):	400,000
Gain on derivative	$ 1,400,000