Investments - Summary of Selected Financial Information for Jefferies LoanCore (Detail) - Jefferies LoanCore, LLC - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2017	Aug. 31, 2016	Nov. 30, 2016
Schedule of Equity Method Investments [Line Items]
Our total equity balance	$ 208,900		$ 208,900		$ 156,300
Net earnings (loss)	3,800	$ 13,400	12,400	$ 36,100
Interest income and fees	0	1,803	589	6,943
Service fees	$ 47	$ 47	$ 142	$ 142
Reverse repurchase agreements					$ 68,100