Selected Quarterly Financial Data (Unaudited) - Summary of Unaudited Quarterly Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2018	May 31, 2018	Feb. 28, 2018	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2017
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 1,073,536	$ 1,141,631	$ 1,314,493	$ 1,054,872	$ 1,097,943	$ 1,088,285	$ 1,156,809	$ 1,086,595	$ 4,584,532	$ 4,429,632	$ 4,178,582
Net revenues	747,802	777,159	901,851	685,718	761,958	777,615	822,557	821,246	3,112,530	3,183,376	3,198,109
Earnings before income taxes	23,871	83,075	155,138	62,585	77,963	87,101	121,865	122,738	$ 324,669	$ 409,667	$ 504,924
Net earnings (loss) attributable to Jefferies Group LLC	$ 25,160	$ 64,968	$ 109,920	$ 45,981	$ 61,393	$ 60,182	$ 98,004	$ (60,818)