Basis of Presentation and Summary of Significant Accounting Policies (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating lease right-of-use asset	$ 678
Operating lease liability	708
Financing lease liability	95
Fair value of long-term debt	7,500			$ 7,300
Restricted cash	2,299			2,682
Debt	7,392			7,326
Cash held at consolidated affiliated partnerships
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Restricted cash	1,673			2,648
Restricted cash
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Restricted cash	626			34
Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating lease right-of-use asset	51		$ 56
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income		$ (11)
Prior period reclassification adjustment		(59)
Operating lease liability	50		56
Financing lease right-of-use asset			26
Financing lease liability			23
Restricted cash	0			0
Deferred revenue	65			69
Recognition of Deferred Revenue	12	12
Revenue, remaining performance obligation	10
Revenue, current portion of remaining performance obligation	4
Debt	1,196			1,170
Real Estate Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Restricted cash	2			26
Debt	$ 2			2
Automotive Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of leases	2,300
Operating lease right-of-use asset	$ 560		589
Operating lease liability	591		621
Financing lease right-of-use asset			24
Financing lease liability			27
Restricted cash	0			0
Deferred revenue	41			42
Recognition of Deferred Revenue	6	4
Debt	405			372
Food Packaging Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating lease right-of-use asset	41		42
Operating lease liability	41		42
Financing lease right-of-use asset			1
Financing lease liability			1
Restricted cash	1			1
Debt	$ 271			273
Other Segments
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating lease right-of-use asset			28
Operating lease liability			$ 28
Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Percentage of equity ownership in operating subsidiary	99.00%
Restricted cash	$ 2,299			2,682
Debt	7,396			7,330
Cash and cash equivalents | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	97			415
Cash held at consolidated affiliated partnerships and restricted cash | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	2,286			2,648
Investments | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	7,130			6,951
Due from brokers | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	1,224			664
Property, plant and equipment, net
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Financing lease right-of-use asset	81			51
Property, plant and equipment, net | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				(15)
Property, plant and equipment, net | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	1,164			3,012
Deferred tax liability | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				18
Total equity | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				75	$ 118
Inventories, net | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	72			380
Intangible assets, net | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	266			278
Other assets
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating lease right-of-use asset	678			0
Other assets | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				108
Other assets | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	55			971
Accounts payable, accrued expenses and other liabilities | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Liabilities of VIE's	851			534
Securities sold, not yet purchased, at fair value | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Liabilities of VIE's	447			468
Due to brokers | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Liabilities of VIE's	0			141
Debt
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Financing lease liability	95			54
Debt | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Liabilities of VIE's	$ 630			1,170
Attributable to Icahn Enterprises | Total equity | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				$ 31	$ 62
Attributable to Icahn Enterprises | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income		(5)
Cost of goods sold | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income		14
Income tax expense | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income		$ (3)
Minimum | Real Estate Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Description of Lessor Leasing Arrangements, Operating Leases	5 years
Maximum | Real Estate Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Description of Lessor Leasing Arrangements, Operating Leases	39 years