Acquisitions (Schedule Of Pro Forma Statement Of Operations Including Jefferies) (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues	$ 2,511,140,000	$ 2,187,495,000	$ 2,109,793,000	$ 2,385,261,000	$ 261,599,000	$ 199,751,000	$ 721,322,000	$ 251,950,000	$ 9,193,689,000	$ 1,434,622,000	$ 1,203,444,000
Interest expense									92,581,000	111,740,000	123,575,000
Expenses									8,227,169,000	757,167,000	820,504,000
Income from continuing operations before income taxes and income (losses) related to associated companies									966,520,000	677,455,000	382,940,000
Income tax provision									376,494,000	270,316,000	(1,136,968,000)
Income from continuing operations before income (losses) related to associated companies									590,026,000	407,139,000	1,519,908,000
Income related to associated companies, net of income tax									276,279,000	(394,041,000)	380,766,000
Income from continuing operations	450,510,000	116,945,000	(186,656,000)	485,506,000	114,484,000	(293,815,000)	182,513,000	9,916,000	866,305,000	13,098,000	1,900,674,000
Net (income) attributable to the noncontrolling interest	993,000	972,000	297,000	(202,000)	373,000	330,000	(149,000)	(279,000)	2,060,000	275,000	(924,000)
Net (income) attributable to the redeemable noncontrolling interests	2,333,000	(8,632,000)	(9,780,000)	3,844,000					(12,235,000)
Income from continuing operations - basic	$ 1.86	$ 0.45	$ (0.80)	$ 2.00	$ 0.47	$ (1.20)	$ 0.75	$ 0.04	$ 3.50	$ 0.05	$ 7.82
Number of shares used in calculation - basic	244,583	244,583	244,583	244,583	244,583	244,580	244,521	244,082	244,583	244,425	243,379
Income from continuing operations - diluted	$ 1.83	$ 0.44	$ (0.80)	$ 1.97	$ 0.46	$ (1.20)	$ 0.74	$ 0.04	$ 3.45	$ 0.05	$ 7.70
Number of shares used in calculation - diluted	248,922	248,910	244,583	248,945	248,874	244,580	249,026	244,620	248,914	244,573	247,672
Pro Forma [Member] | Jefferies Group Inc [Member]
Revenues									12,969,819,000
Interest expense									825,666,000
Net revenues									12,144,153,000
Expenses									10,684,632,000
Income from continuing operations before income taxes and income (losses) related to associated companies									1,459,521,000
Income tax provision									543,997,000
Income from continuing operations before income (losses) related to associated companies									915,524,000
Income related to associated companies, net of income tax									126,790,000
Income from continuing operations									1,042,314,000
Net (income) attributable to the noncontrolling interest									(38,680,000)
Net (income) attributable to the redeemable noncontrolling interests									(12,235,000)
Preferred stock dividends									(4,063,000)
Net income from continuing operations attributable to Leucadia National Corporation common shareholders									$ 987,336,000
Income from continuing operations - basic									$ 2.60
Number of shares used in calculation - basic									372,549
Income from continuing operations - diluted									$ 2.56
Number of shares used in calculation - diluted									381,045