Investments - Summary of Selected Financial Information for Jefferies LoanCore (Detail) - Jefferies LoanCore - USD ($) $ in Thousands	11 Months Ended	12 Months Ended
	Oct. 31, 2017	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2015
Schedule of Equity Method Investments [Line Items]
Total assets			$ 1,827,200
Total liabilities			1,505,000
Total equity			322,200
Our total equity balance			156,300
Net earnings (loss)	$ 37,500		71,800	$ 79,000
Interest income and fees		$ 588	8,412	10,690
Placement fees		100	100	1,643
Service fees		$ 190	200	$ 241
Reverse repurchase agreements			$ 68,100