Segment Information (Schedule Of Segment Reporting Information, By Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Net Revenues	$ 2,839,463	$ 2,851,963	$ 6,024,146	$ 5,794,487
Total consolidated pre-tax income from continuing operations	463	117,919	587,570	275,015
Depreciation and amortization	55,240	44,643	107,680	86,130
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Revenues	2,801,140	2,717,915	5,268,916	5,549,489
Total consolidated pre-tax income from continuing operations	85,783	81,636	55,258	230,762
Depreciation and amortization	45,340	40,917	90,347	80,045
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net Revenues	0	0	(21,000)	0
Parent Company Interest [Member]
Segment Reporting Information [Line Items]
Total consolidated pre-tax income from continuing operations	(24,310)	(24,366)	(48,610)	(49,543)
Jefferies [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Revenues	792,431	689,303	1,383,872	1,619,815
Total consolidated pre-tax income from continuing operations	91,345	85,568	104,269	281,938
Depreciation and amortization	22,326	18,383	44,576	35,414
National Beef [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Revenues	1,994,865	2,009,093	3,850,884	3,896,471
Total consolidated pre-tax income from continuing operations	(9,400)	6,518	(42,985)	(21,495)
Depreciation and amortization	22,081	21,195	43,868	41,955
Corporate and Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Revenues	13,844	19,519	34,160	33,203
Total consolidated pre-tax income from continuing operations	3,838	(10,450)	(6,026)	(29,681)
Depreciation and amortization	933	1,339	1,903	2,676
All other (Member) [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Revenues	38,323	134,048	776,230	244,998
Total consolidated pre-tax income from continuing operations	(61,010)	60,649	580,922	93,796
Depreciation and amortization	$ 9,900	$ 3,726	$ 17,333	$ 6,085