Earnings (Loss) Per Common Share (Earnings Per Share Computation) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Line Items]
Net income (loss) attributable to Leucadia National Corporation common shareholders	$ 281,408	$ (222,880)
Allocation of earnings to participating securities	(1,138)	0
Net income (loss) attributable to Leucadia National Corporation common shareholders for basic earnings (loss) per share	280,270	(222,880)
Adjustment to allocation of earnings to participating securities related to diluted shares	8	0
Mandatorily redeemable convertible preferred share dividends	1,016	0
Net income (loss) attributable to Leucadia National Corporation common shareholders for diluted earnings (loss) per share	$ 281,294	$ (222,880)
Denominator for basic earnings (loss) per share - weighted average shares	369,267,000	372,367,000
Dilutive effect of share-based payment awards	16,000	0
Warrants	0	0
Mandatorily redeemable convertible preferred shares	4,162,000	0
Denominator for diluted earnings (loss) per share	375,721,000	372,367,000
Weighted average shares of participating securities	1,500,000	2,899,000
3.875% Convertible Senior Debentures, due November 1, 2029 [Member]
Earnings Per Share [Line Items]
Convertible Senior Debenture	0	0
Senior Executive Compensation Plan [Member]
Earnings Per Share [Line Items]
Dilutive effect of share-based payment awards	2,276,000	0