Common Share and Earnings (Loss) Per Common Share (Earnings Per Share Computation) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator for earnings per share:
Net income attributable to Leucadia National Corporation common shareholders	$ 124,525	$ 281,408
Allocation of earnings to participating securities	(499)	(1,138)
Net income attributable to Leucadia National Corporation common shareholders for basic earnings per share	124,026	280,270
Adjustment to allocation of earnings to participating securities related to diluted shares	(1)	8
Mandatorily redeemable convertible preferred share dividends	1,172	1,016
Net income attributable to Leucadia National Corporation common shareholders for diluted earnings per share	$ 125,197	$ 281,294
Denominator for earnings per share:
Weighted average common shares outstanding	356,576,000	359,634,000
Denominator for basic earnings per share – weighted average shares	366,427,000	369,267,000
Mandatorily redeemable convertible preferred shares (in shares)	4,162,000	4,162,000
Denominator for diluted earnings (loss) per share (in shares)	373,461,000	375,721,000
Weighted average shares of participating securities (in shares)	1,317,000	1,500,000
Restricted Stock with Future Service Required
Denominator for earnings per share:
Weighted average shares of restricted stock outstanding with future service required	(1,285,000)	(1,432,000)
Restricted Stock Units with No Future Service Required
Denominator for earnings per share:
Weighted average RSUs outstanding with no future service required (in shares)	11,136,000	11,065,000
Stock options
Denominator for earnings per share:
Dilutive effect of share-based payment awards (in shares)	30,000	16,000
Restricted Stock Units | Senior Executive Compensation Plan
Denominator for earnings per share:
Dilutive effect of share-based payment awards (in shares)	2,842,000	2,276,000