Common Shares and Earnings (Loss) Per Common Share (Earnings Per Share Computation) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Leucadia National Corporation common shareholders	$ 137,171	$ 154,358	$ 57,289	$ (222,880)	$ 55,595	$ (173,173)	$ 16,406	$ 380,759	$ 125,938	$ 279,587	$ 204,306
Allocation of earnings to participating securities									(574)	(4,711)	(4,761)
Net income attributable to Leucadia National Corporation common shareholders for basic earnings (loss) per share									125,364	274,876	199,545
Adjustment to allocation of earnings to participating securities related to diluted shares									(19)	(34)	(75)
Mandatorily redeemable convertible preferred share dividends									0	0	0
Interest on 3.75% Convertible Notes									0	0	739
Net income attributable to Leucadia National Corporation common shareholders for diluted earnings (loss) per share									$ 125,345	$ 274,842	$ 200,209
Denominator for basic earnings (loss) per share – weighted average shares (shares)	369,299,000	370,404,000	372,556,000	372,367,000	369,840,000	372,547,000	373,654,000	373,541,000	371,211,000	372,430,000	371,889,000
Warrants (shares)									0	0	0
Mandatorily redeemable convertible preferred shares (shares)									0	0	0
Denominator for diluted earnings (loss) per share (shares)	374,693,000	374,567,000	372,556,000	372,367,000	369,840,000	372,547,000	373,662,000	377,713,000	371,518,000	372,431,000	373,333,000
Weighted average shares of participating securities									1,986,800	6,500,000	9,040,900
Dividends declared on participating securities									$ 400	$ 1,500	$ 2,200
3.875% Convertible Senior Debentures, due November 1, 2029 [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Convertible Debenture/Notes (shares)									0	0	0
3.75% Convertible Senior Subordinated Notes Due April 15, 2014 [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Convertible Debenture/Notes (shares)									0	0	1,415,000
Employee Stock Option [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of share-based payment arrangements (shares)									0	1,000	29,000
Restricted Stock Units (RSUs) [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive effect of share-based payment arrangements (shares)									307,000	0	0