Basis of Presentation and Summary of Significant Accounting Policies (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt	$ 8,658		$ 8,658			$ 7,326
Fair value of long-term debt	8,800		8,800			7,300
Cash held at consolidated affiliated partnerships and restricted cash	664		664			2,682
Operating lease right-of-use asset	654		654
Operating lease liability	685		685
Financing lease liability	93		93
Cash held at consolidated affiliated partnerships
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cash held at consolidated affiliated partnerships and restricted cash	133		133			2,648
Restricted cash
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cash held at consolidated affiliated partnerships and restricted cash	531		531			34
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		$ (11)		$ (22)
Debt	1,195		1,195			1,170
Cash held at consolidated affiliated partnerships and restricted cash	0		0			0
Deferred revenue	9		9			69
Recognition of beginning deferred revenue	56	20	68	32
Revenue, remaining performance obligation	8		8
Revenue, current portion of remaining performance obligation	2		2
Operating lease right-of-use asset	47		47		$ 56
Operating lease liability	46		46		56
Financing lease right-of-use asset					26
Financing lease liability					23
Real Estate Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt	2		2			2
Cash held at consolidated affiliated partnerships and restricted cash	2		2			26
Automotive Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt	406		406			372
Cash held at consolidated affiliated partnerships and restricted cash	0		0			0
Deferred revenue	42		42			42
Recognition of beginning deferred revenue	$ 6	6	$ 12	12
Number of leases	2,300		2,300
Operating lease right-of-use asset	$ 541		$ 541		589
Operating lease liability	569		569		621
Financing lease right-of-use asset					24
Financing lease liability					27
Food Packaging Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt	270		270			273
Cash held at consolidated affiliated partnerships and restricted cash	1		1			1
Operating lease right-of-use asset	33		33		35
Operating lease liability	37		$ 37		39
Financing lease right-of-use asset					1
Financing lease liability					1
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%
Debt	8,663		$ 8,663			7,330
Cash held at consolidated affiliated partnerships and restricted cash	664		664			2,682
Cash and cash equivalents | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	69		69			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	651		651			2,648
Investments | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	8,273		8,273			6,951
Due from brokers | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	1,280		1,280			664
Property, plant and equipment, net
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Financing lease right-of-use asset	79		79			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	1,554		1,554			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	56		56			380
Intangible assets, net | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Assets of VIE's	268		268			278
Other assets
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Operating lease right-of-use asset	654		654			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	228		228			971
Accounts payable, accrued expenses and other liabilities | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Liabilities of VIE's	972		972			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	146		146			468
Due to brokers | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Liabilities of VIE's	14		14			141
Debt
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Financing lease liability	93		93			51
Debt | Icahn Enterprises Holdings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Liabilities of VIE's	$ 631		$ 631			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		(7)		(12)
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		(2)		(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		13		27
Prior period reclassification adjustment		11		70
Other income, net | Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Prior period reclassification adjustment		(11)		(70)
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
Discontinued operations, held for sale or disposed of by sale
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Income tax expense from discontinued operations		27		63
Discontinued operations, held for sale or disposed of by sale | Federal-Mogul
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Income tax expense from discontinued operations		$ 18	$ (24)	$ 41