Investments - Summary of Selected Financial Information for Jefferies Finance (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2020	Aug. 31, 2019	Nov. 30, 2019
Schedule of Equity Method Investments [Line Items]
Net earnings (loss)	$ 267,531	$ 64,825	$ 567,792	$ 221,009
Jefferies Finance, LLC
Schedule of Equity Method Investments [Line Items]
Interest income	0	0	2,200	0
Unfunded commitment fees	400	300	800	900
Our total equity balance	591,000		591,000		$ 642,000
Origination and syndication fee revenues	42,400	44,600	123,900	135,800
Origination fee expenses	3,800	8,200	12,400	21,800
CLO placement fee revenues	1,300	1,000	1,700	2,300
Underwriting fees	0	2,900	300	3,900
Service fees	13,500	12,300	49,400	50,600
Jefferies Finance, LLC | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net earnings (loss)	$ (23,600)	$ (16,300)	$ (102,100)	$ 31,500