Basis of Presentation and Summary of Significant Accounting Policies Narrative (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019	Jan. 01, 2018
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt	$ 7,326				$ 7,372				$ 7,326	$ 7,372
Fair value of long-term debt	7,300				7,600				$ 7,300	7,600
Affiliate ownership interest									98.01%
Cash held at consolidated affiliated partnerships and restricted cash	2,682				747				$ 2,682	747
Portion of inventory under LIFO method	846				900				846	900
Post-retirement benefit liability	77				80				77	80
Accumulated other comprehensive loss	(84)				(1,384)				(84)	(1,384)
Cumulative effect adjustment from adoption of accounting principal									(29)	(47)
Accounts receivable, net	474				473				474	473
Accrued expenses and other liabilities	900				984				900	984
Deferred tax liability	676				732				676	732
Net sales	2,578	$ 2,815	$ 2,820	$ 2,363	2,385	$ 2,334	$ 2,277	$ 2,310	10,576	9,306	$ 7,740
Cost of goods sold									8,947	8,258	6,837
Assets	23,396				31,801				23,396	31,801
Liabilities	10,491				20,433				10,491	20,433
Cash held at consolidated affiliated partnerships [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cash held at consolidated affiliated partnerships and restricted cash	2,648				192				2,648	192
Restricted cash
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cash held at consolidated affiliated partnerships and restricted cash	34				555				34	555
Automotive Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt	372				340				372	340
Cash held at consolidated affiliated partnerships and restricted cash	0				0				0	0
Deferred revenue	42								42				$ 42
Revenue recognition during period of previously deferred revenue									22
Deferred revenue expected to be earned within one year	22								22
Accounts receivable, net	149				128				149	128
Net sales									2,295	2,225	2,079
Cost of goods sold									1,502	1,540	1,430
Assets	3,024				3,011				3,024	3,011
Liabilities	1,277				1,284				1,277	1,284
Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt	1,170				1,166				1,170	1,166
Cash held at consolidated affiliated partnerships and restricted cash	0				0				0	0
Planned major maintenance									10	83	38
Remaining performance obligation for contracts with an original expected duration of more than one year	11								11
Remaining performance obligation expected to be recognized as revenue within one year	5								5
Deferred revenue	69								69				34
Revenue recognition during period of previously deferred revenue									34
Accounts receivable, net	169				179				169	179
Net sales									7,124	5,988	4,782
Cost of goods sold									6,453	5,799	4,637
Assets	4,738				4,700				4,738	4,700
Liabilities	2,195				2,291				2,195	2,291
Net cash provided by operating activities
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Prior Period Reclassification Adjustment										(19)	(446)
Difference between Revenue Guidance in Effect before and after Topic 606
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets													32
Difference between Revenue Guidance in Effect before and after Topic 606 | Automotive Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Accounts receivable, net													21
Net sales									62
Cost of goods sold									$ 62
Liabilities													(29)
Selling, general and administrative
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Prior Period Reclassification Adjustment										(4)	(4)
Other Income, net
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Prior Period Reclassification Adjustment										(4)	(4)
Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Percentage of equity ownership in operating subsidiary									99.00%
Debt	7,330				7,377				$ 7,330	7,377
Cash held at consolidated affiliated partnerships and restricted cash	2,682				747				2,682	747
Cumulative effect adjustment from adoption of accounting principal									(29)	(47)
Accounts receivable, net	474				473				474	473
Accrued expenses and other liabilities	900				984				900	984
Deferred tax liability	676				732				676	732
Net sales									10,576	9,306	7,740
Cost of goods sold									8,947	8,258	$ 6,837
Assets	23,428				31,833				23,428	31,833
Liabilities	$ 10,495				$ 20,438				$ 10,495	$ 20,438
CVR Energy
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Percentage of equity ownership in operating subsidiary									70.80%
Extended warranties | Difference between Revenue Guidance in Effect before and after Topic 606 | Automotive Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Accrued expenses and other liabilities													(42)
Deferred tax liability													$ 10
Subsequent event | Automotive Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating lease right-of-use asset												$ 639
Operating lease liability												674
Subsequent event | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating lease right-of-use asset												53
Operating lease liability												53
Finance lease right-of-use asset												$ 26
Minimum | Nitrogenous fertilizer manufacturing | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Planned major maintenance, frequency (in years)									2 years
Minimum | Petroleum refineries | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Planned major maintenance, frequency (in years)									4 years
Minimum | CVR Energy
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Performance obligation payment terms									2 days
Maximum | Nitrogenous fertilizer manufacturing | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Planned major maintenance, frequency (in years)									3 years
Maximum | Petroleum refineries | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Planned major maintenance, frequency (in years)									5 years
Maximum | CVR Energy
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Performance obligation payment terms									30 days
Icahn Enterprises G.P.
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Aggregate general partner ownership interest of parent and operating subsidiary									1.99%
General partner ownership percentage in Icahn Enterprises									1.00%
Icahn Enterprises G.P. | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
General partner ownership percentage in Icahn Enterprises									1.00%