Investments - Jefferies Finance - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
Feb. 29, 2020	Nov. 30, 2019
Guarantee Obligations [Line Items]
Financial instruments owned, at fair value	$ 17,897,386	$ 16,363,374
Payables-brokers, dealers and clearing organizations	4,186,467	2,555,178
Financial instruments sold, not yet purchased, at fair value ($4,240 and $0 at February 29, 2020 and November 30, 2019, respectively, related to consolidated VIEs)	9,877,182	10,532,460
Jefferies Finance, LLC
Guarantee Obligations [Line Items]
Equity commitment	750,000
Total committed equity capitalization of JFIN	1,500,000
Funded portion of equity commitment to subsidiary	652,400
Unfunded portion of equity commitment to subsidiary	$ 97,600
Extension period	1 year
Termination notice period	60 days
Funded portion of loan commitment	$ 0
Loan commitment	250,000
Jefferies Finance, LLC \| Corporate debt securities
Guarantee Obligations [Line Items]
Committed line of credit facility amount	500,000
Jefferies Finance, LLC \| Other Assets
Guarantee Obligations [Line Items]
Receivables under service agreement	18,300	17,200
Jefferies Finance, LLC \| Accrued expense and other liabilities
Guarantee Obligations [Line Items]
Payables under service agreement	(13,700)	(13,700)
Jefferies Finance, LLC \| Payables to customers
Guarantee Obligations [Line Items]
Payables under service agreement	(8,500)	(17,600)
Foreign exchange contracts \| Jefferies Finance, LLC
Guarantee Obligations [Line Items]
Financial instruments owned, at fair value	400
Payables-brokers, dealers and clearing organizations		4,700
Financial instruments sold, not yet purchased, at fair value ($4,240 and $0 at February 29, 2020 and November 30, 2019, respectively, related to consolidated VIEs)		$ 200
Gain on derivatives	$ 1,400

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