Investments - Jefferies Finance - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended
	Feb. 28, 2018	Nov. 30, 2017
Guarantee Obligations [Line Items]
Financial instruments sold, not yet purchased, at fair value	$ 9,630,413	$ 8,171,929
Financial instruments owned, at fair value	15,318,223	14,193,352
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	657,400
Unfunded portion of equity commitment to subsidiary	$ 92,600
Extension period	1 year
Termination notice period	60 days
Funded portion of loan commitment	$ 121,200
Loan commitment	250,000
Financial instruments sold, not yet purchased, at fair value	400
Financial instruments owned, at fair value		1,500
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	43,100	$ 20,500
Jefferies Finance, LLC | Accrued expense and other liabilities
Guarantee Obligations [Line Items]
Payables under service agreement	$ 14,100