Investments - Jefferies Finance - Narrative (Details) - USD ($)		3 Months Ended		9 Months Ended
	May 15, 2019	Aug. 31, 2019	Aug. 31, 2018	Aug. 31, 2019	Aug. 31, 2018	Mar. 28, 2019	Nov. 30, 2018
Guarantee Obligations [Line Items]
Financial instruments sold, not yet purchased, at fair value		$ 10,296,315,000		$ 10,296,315,000			$ 9,478,944,000
Payables-brokers, dealers and clearing organizations		2,253,033,000		2,253,033,000			2,448,059,000
Interest expense		364,472,000	$ 310,670,000	1,146,268,000	$ 910,271,000
Jefferies Finance, LLC
Guarantee Obligations [Line Items]
Equity commitment		750,000,000.0		750,000,000.0
Total committed equity capitalization of JFIN		1,500,000,000		1,500,000,000
Funded portion of equity commitment to subsidiary		643,700,000		643,700,000
Unfunded portion of equity commitment to subsidiary		106,300,000		$ 106,300,000
Extension period				1 year
Termination notice period				60 days
Funded portion of loan commitment		0.0		$ 0.0
Loan commitment		250,000,000.0		250,000,000.0
Financial instruments sold, not yet purchased, at fair value		2,100,000		2,100,000			400,000
Payables-brokers, dealers and clearing organizations							200,000
Jefferies Finance, LLC | Corporate debt securities
Guarantee Obligations [Line Items]
Committed line of credit facility amount		500,000,000.0		500,000,000.0
Jefferies Finance, LLC | Other Assets
Guarantee Obligations [Line Items]
Receivables under service agreement		12,900,000		12,900,000			35,200,000
Jefferies Finance, LLC | Accrued expense and other liabilities
Guarantee Obligations [Line Items]
Payables under service agreement		$ 13,700,000		$ 13,700,000			$ 14,100,000
Promissory Note
Guarantee Obligations [Line Items]
Debt principal amount						$ 1,000,000,000.0
Interest expense	$ 3,800,000