Basis of Presentation and Summary of Significant Accounting Policies (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Accounting policies [Line Items]
Debt		$ 7,449			$ 7,326
Fair value of long-term debt		7,700			7,300
Cash held at consolidated affiliated partnerships and restricted cash		613			2,682
Operating lease right-of-use asset		635
Operating lease liability		664
Financing lease liability		93
Cash held at consolidated affiliated partnerships
Accounting policies [Line Items]
Cash held at consolidated affiliated partnerships and restricted cash		286			2,648
Restricted cash
Accounting policies [Line Items]
Cash held at consolidated affiliated partnerships and restricted cash		327			34
Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	$ (11)		$ (33)
Debt		1,195			1,170
Cash held at consolidated affiliated partnerships and restricted cash		0			0
Deferred revenue		16			69
Recognition of beginning deferred revenue		68	34
Revenue, remaining performance obligation		7
Revenue, current portion of remaining performance obligation		1
Operating lease right-of-use asset		48		$ 56
Operating lease liability		47		56
Financing lease right-of-use asset				26
Financing lease liability				23
Automotive Segment
Accounting policies [Line Items]
Debt		403			372
Cash held at consolidated affiliated partnerships and restricted cash		0			0
Deferred revenue		42			42
Recognition of beginning deferred revenue		$ 17	18
Number of leases		2,300
Operating lease right-of-use asset		$ 521		589
Operating lease liability		547		621
Financing lease right-of-use asset				20
Financing lease liability				22
Real Estate Segment
Accounting policies [Line Items]
Debt		2			2
Cash held at consolidated affiliated partnerships and restricted cash		2			26
Food Packaging Segment
Accounting policies [Line Items]
Debt		269			273
Cash held at consolidated affiliated partnerships and restricted cash		1			1
Operating lease right-of-use asset		34		35
Operating lease liability		$ 38		39
Financing lease liability				0
Other Segments
Accounting policies [Line Items]
Operating lease right-of-use asset				28
Operating lease liability				$ 28
Icahn Enterprises Holdings
Accounting policies [Line Items]
Percentage of equity ownership in operating subsidiary		99.00%
Debt		$ 7,452			7,330
Cash held at consolidated affiliated partnerships and restricted cash		613			2,682
Cash and cash equivalents | Icahn Enterprises Holdings
Accounting policies [Line Items]
Assets of VIE's		84			415
Cash held at consolidated affiliated partnerships and restricted cash | Icahn Enterprises Holdings
Accounting policies [Line Items]
Assets of VIE's		600			2,648
Investments | Icahn Enterprises Holdings
Accounting policies [Line Items]
Assets of VIE's		8,718			6,951
Due from brokers | Icahn Enterprises Holdings
Accounting policies [Line Items]
Assets of VIE's		842			664
Inventories, net | Icahn Enterprises Holdings
Accounting policies [Line Items]
Assets of VIE's		57			380
Property, plant and equipment, net
Accounting policies [Line Items]
Financing lease right-of-use asset		80			41
Property, plant and equipment, net | Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					(15)
Property, plant and equipment, net | Icahn Enterprises Holdings
Accounting policies [Line Items]
Assets of VIE's		1,125			3,012
Deferred tax liability | Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					18
Total equity | Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					75	$ 118
Intangible assets, net | Icahn Enterprises Holdings
Accounting policies [Line Items]
Assets of VIE's		256			278
Other assets
Accounting policies [Line Items]
Operating lease right-of-use asset		635			0
Other assets | Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					108
Other assets | Icahn Enterprises Holdings
Accounting policies [Line Items]
Assets of VIE's		345			930
Accounts payable, accrued expenses and other liabilities | Icahn Enterprises Holdings
Accounting policies [Line Items]
Liabilities of VIE's		1,481			516
Securities sold, not yet purchased, at fair value | Icahn Enterprises Holdings
Accounting policies [Line Items]
Liabilities of VIE's		223			468
Due to brokers | Icahn Enterprises Holdings
Accounting policies [Line Items]
Liabilities of VIE's		114			141
Debt
Accounting policies [Line Items]
Financing lease liability		93			52
Debt | Icahn Enterprises Holdings
Accounting policies [Line Items]
Liabilities of VIE's		$ 632			1,167
Attributable to Icahn Enterprises | Total equity | Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification					$ 31	$ 62
Attributable to Icahn Enterprises | Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	(8)		(20)
Income tax expense | Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	(3)		(8)
Cost of goods sold | Energy Segment
Accounting policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	14		41
Prior period reclassification adjustment	5		75
Other income, net | Energy Segment
Accounting policies [Line Items]
Prior period reclassification adjustment	(5)		(75)
Minimum | Real Estate Segment
Accounting policies [Line Items]
Description of Lessor Leasing Arrangements, Operating Leases		5 years
Maximum | Real Estate Segment
Accounting policies [Line Items]
Description of Lessor Leasing Arrangements, Operating Leases		39 years
Discontinued operations, held for sale or disposed of by sale
Accounting policies [Line Items]
Income tax expense from discontinued operations	(37)		(100)
Discontinued operations, held for sale or disposed of by sale | Federal-Mogul
Accounting policies [Line Items]
Income tax expense from discontinued operations	$ (28)	$ (24)	$ (69)