Schedule I - Condensed Financial Information of Registrant - Condensed Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Principal transactions									$ 931,576	$ 603,822	$ 642,824
Other									748,508	488,186	549,228
Total revenues									12,407,854	10,875,254	11,683,927
Expenses:
Compensation and benefits									1,993,776	1,730,585	1,665,465
Interest									107,859	108,703	115,804
Selling, general and other expenses									817,620	831,892	757,788
Total expenses									10,347,678	9,900,785	10,640,203
Income (loss) related to associated companies									(74,901)	154,598	110,281
Income tax provision (benefit)									760,967	122,109	109,947
Income from continuing operations									167,351	125,938	274,065
Preferred stock dividends	$ (1,172)	$ (1,172)	$ (1,015)	$ (1,016)	$ (1,016)	$ (1,016)	$ (1,015)	$ (1,016)	(4,375)	(4,063)	(4,063)
Net income attributable to Leucadia National Corporation common shareholders	$ (271,601)	$ 99,351	$ 58,193	$ 281,408	$ 137,171	$ 154,358	$ 57,289	$ (222,880)	$ 167,351	$ 125,938	$ 279,587
Basic earnings per common share attributable to Leucadia National Corporation common shareholders:
Income from continuing operations (USD per share)									$ 0.45	$ 0.34	$ 0.73
Income from discontinued operations (USD per share)									0.00	0.00	0.00
Gain on disposal of discontinued operations (USD per share)									0.00	0.00	0.01
Net income (USD per share)	$ (0.74)	$ 0.27	$ 0.16	$ 0.76	$ 0.37	$ 0.41	$ 0.15	$ (0.60)	0.45	0.34	0.74
Diluted earnings per common share attributable to Leucadia National Corporation common shareholders:
Income from continuing operations (USD per share)									0.45	0.34	0.73
Income from discontinued operations (USD per share)									0.00	0.00	0.00
Gain on disposal of discontinued operations (USD per share)									0.00	0.00	0.01
Net income (USD per share)	$ (0.74)	$ 0.27	$ 0.16	$ 0.75	$ 0.37	$ 0.41	$ 0.15	$ (0.60)	0.45	0.34	0.74
Dividends per common share (USD per share)									$ 0.3250	$ 0.25	$ 0.25
Parent Company
Revenues:
Principal transactions									$ (9,754)	$ 16,735	$ 491,341
Other									277	2,300	1,477
Total revenues									(9,477)	19,035	492,818
Expenses:
Compensation and benefits									47,462	39,693	58,899
WilTel pension									2,957	2,989	50,836
Interest									58,943	58,881	87,181
Intercompany interest expense									361,446	293,527	241,906
Selling, general and other expenses									20,821	19,244	26,784
Total expenses									491,629	414,334	465,606
Income (loss) from continuing operations before income taxes, income related to associated companies and equity in earnings of subsidiaries									(501,106)	(395,299)	27,212
Income (loss) related to associated companies									3,183	21,195	3,479
Income (loss) from continuing operations before income taxes and equity in earnings of subsidiaries									(497,923)	(374,104)	30,691
Income tax provision (benefit)									(47,329)	(117,699)	267
Income (loss) from continuing operations before equity in earnings of subsidiaries									(450,594)	(256,405)	30,424
Equity in earnings of subsidiaries, net of taxes									622,320	386,406	247,704
Income from continuing operations									171,726	130,001	278,128
Equity in income from discontinued operations, net of taxes									0	0	429
Equity in gain on disposal of discontinued operations, net of taxes									0	0	5,093
Net income									171,726	130,001	283,650
Preferred stock dividends									(4,375)	(4,063)	(4,063)
Net income attributable to Leucadia National Corporation common shareholders									$ 167,351	$ 125,938	$ 279,587
Basic earnings per common share attributable to Leucadia National Corporation common shareholders:
Income from continuing operations (USD per share)									$ 0.45	$ 0.34	$ 0.73
Income from discontinued operations (USD per share)									0.00	0.00	0.00
Gain on disposal of discontinued operations (USD per share)									0.00	0.00	0.01
Net income (USD per share)									0.45	0.34	0.74
Diluted earnings per common share attributable to Leucadia National Corporation common shareholders:
Income from continuing operations (USD per share)									0.45	0.34	0.73
Income from discontinued operations (USD per share)									0.00	0.00	0.00
Gain on disposal of discontinued operations (USD per share)									0.00	0.00	0.01
Net income (USD per share)									0.45	0.34	0.74
Dividends per common share (USD per share)									$ 0.325	$ 0.250	$ 0.250