Description of Business (Details) $ in Millions						1 Months Ended			3 Months Ended	12 Months Ended
	Jul. 31, 2019	Jan. 29, 2019 USD ($)	Dec. 05, 2018 USD ($)	Oct. 01, 2018 USD ($) shares	Aug. 01, 2018 USD ($) shares	Oct. 31, 2020 USD ($) shares	Aug. 31, 2018 USD ($)	Jan. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Description of Business [Line Items]
Aggregate general partner ownership interest of parent and operating subsidiary										1.99%
Purchase of additional interests in consolidated subsidiaries											$ (241)	$ (5)
(Loss) gain on disposition of assets, net										$ (17)	253	84
Proceeds from disposition of businesses and assets										25	505	3,370
Energy Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net										(7)	4	(6)
Automotive Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net										(6)	(4)	(1)
Food Packaging Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net										0
Real Estate Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net							$ 89			(5)		89
Proceeds from disposition of businesses and assets							$ 179
Railcar Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net										0		5
Mining Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net										0	$ 252	(3)
Pharma Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net										$ 0
Icahn Enterprises Holdings
Description of Business [Line Items]
Percentage of equity ownership in operating subsidiary										99.00%
General partner ownership percentage in Icahn Enterprises										1.00%
Aggregate general partner ownership interest of parent and operating subsidiary										1.00%
Affiliate ownership interest										99.00%
Icahn Enterprises G.P.
Description of Business [Line Items]
General partner ownership percentage in Icahn Enterprises										1.00%
Aggregate general partner ownership interest of parent and operating subsidiary										1.99%
Affiliate ownership interest										98.01%
Icahn Enterprises G.P. | Mining Segment
Description of Business [Line Items]
Percentage of equity ownership in operating subsidiary	77.00%
CVR Refining
Description of Business [Line Items]
Percentage of equity ownership in operating subsidiary										36.00%
CVR Refining | Energy Segment
Description of Business [Line Items]
Percentage of equity ownership in operating subsidiary		4.00%
CVR Energy | Energy Segment
Description of Business [Line Items]
Percentage of equity ownership in operating subsidiary		81.00%								71.00%
Viskase | Private Placement
Description of Business [Line Items]
Percentage of equity ownership in operating subsidiary										89.00%	79.00%
Common stock shares acquired | shares						50,000,000
Amount of common stock shares acquired						$ 100
Viskase | Food Packaging Segment
Description of Business [Line Items]
Percentage of equity ownership in operating subsidiary										79.00%	75.00%
Investment Funds
Description of Business [Line Items]
Fair value of investment in subsidiary										$ 4,300	$ 4,300
Mr. Icahn and affiliates
Description of Business [Line Items]
Affiliate ownership interest										92.00%
CVR Refining | Energy Segment
Description of Business [Line Items]
Purchase of additional interests in consolidated subsidiaries		$ 241
Common units validly tendered and not properly withdrawn | shares					21,625,106
CVR Energy | Energy Segment
Description of Business [Line Items]
Equity issued to acquire additional interest in consolidated subsidiary (number of units) | shares					13,699,549
Change in equity as a result of acquisition of additional interest in consolidated subsidiary					$ 99
Viskase | Food Packaging Segment
Description of Business [Line Items]
Proceeds from rights offering								$ 50
Contribution to subsidiary								$ 44
ARL | Railcar Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net												5
aggregate consideration for business disposed of									$ 17			$ 17
Ferrous Resources | Mining Segment
Description of Business [Line Items]
(Loss) gain on disposition of assets, net											$ 252
Proceeds from disposition of businesses and assets										$ 463
Aggregate consideration for business to be disposed of			$ 550
Federal-Mogul
Description of Business [Line Items]
(Loss) gain on disposition of assets, net									251
Proceeds from disposition of businesses and assets				$ 800
consideration in shares for business disposed of | shares				29,500,000
consideration in non-voting shares for business disposed of | shares				23,800,000
consideration in voting shares for business disposed of | shares				5,700,000
fair market value of shares obtained as consideration for business disposed of				$ 1,200
Tropicana
Description of Business [Line Items]
(Loss) gain on disposition of assets, net									779
Proceeds from disposition of businesses and assets				1,500
aggregate consideration for business disposed of				$ 1,800
ARI
Description of Business [Line Items]
(Loss) gain on disposition of assets, net									$ 400
Proceeds from disposition of businesses and assets			$ 831
Vivus | Pharma Segment
Description of Business [Line Items]
Number Of Approved Therapies | item										2
Number Of Product Candidate In Active Clinical Development | item										1
Fair value of debt securities										$ 183
Contingent Liability										3
Consideration Including Exit policy										81
Repayments of Debt										$ 63