Investments - Jefferies Finance - Narrative (Details) - USD ($)		3 Months Ended		9 Months Ended
	May 15, 2019	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2020	Aug. 31, 2019	Nov. 30, 2019	Mar. 28, 2019
Guarantee Obligations [Line Items]
Interest expense		$ 211,629,000	$ 364,472,000	$ 753,405,000	$ 1,146,268,000
Promissory Note
Guarantee Obligations [Line Items]
Debt principal amount							$ 1,000,000,000.0
Interest expense	$ 3,800,000
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		652,400,000		652,400,000
Unfunded portion of equity commitment to subsidiary		97,600,000		$ 97,600,000
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
Jefferies Finance, LLC | Other assets
Guarantee Obligations [Line Items]
Receivables under service agreement		13,200,000		13,200,000		$ 17,200,000
Jefferies Finance, LLC | Accrued expense and other liabilities
Guarantee Obligations [Line Items]
Payables under service agreement		13,700,000		13,700,000		13,700,000
Jefferies Finance, LLC | Payables to customers
Guarantee Obligations [Line Items]
Payables under service agreement						$ 17,600,000
Jefferies Finance, LLC | Corporate debt securities
Guarantee Obligations [Line Items]
Committed line of credit facility amount		$ 500,000,000.0		$ 500,000,000.0