Selected Quarterly Financial Data (Unaudited) - Summary of Unaudited Quarterly Statements of Earnings (Detail) - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2015	Aug. 31, 2015	May. 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 701,930	$ 781,123	$ 1,008,510	$ 783,332	$ 723,004	$ 1,055,435	$ 970,786	$ 1,097,040
Net revenues	513,087	578,928	791,554	591,672	524,809	843,309	722,992	899,028
Earnings (loss) before income taxes	9,538	7,093	84,712	12,884	(114,020)	135,635	99,137	182,269
Net earnings (loss) attributable to Jefferies Group LLC	$ 19,962	$ 2,057	$ 59,833	$ 11,682	$ (99,759)	$ 83,561	$ 61,326	$ 112,432