Fair Value Measurements - Fair Value Measurement (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets [Abstract]
Derivative contracts, at fair value (asset)	$ 785	$ 182
Liabilities [Abstract]
Securities sold, not yet purchased, at fair value	2,521	1,190
Derivative contracts, at fair value (liability)	639	1,224
Recurring measurement
Assets [Abstract]
Investments	8,761	9,732
Derivative contracts, at fair value (asset)	785	182
Assets, Fair Value Disclosure	9,546	9,914
Liabilities [Abstract]
Securities sold, not yet purchased, at fair value	2,521	1,190
Derivative contracts, at fair value (liability)	639	1,224
Other liabilities	214	13
Financial and Nonfinancial Liabilities, Fair Value Disclosure	3,374	2,427
Recurring measurement \| Level 1
Assets [Abstract]
Investments	8,546	9,448
Assets, Fair Value Disclosure	8,546	9,448
Liabilities [Abstract]
Securities sold, not yet purchased, at fair value	2,521	1,190
Derivative contracts, at fair value (liability)	11
Financial and Nonfinancial Liabilities, Fair Value Disclosure	2,532	1,190
Recurring measurement \| Level 2
Assets [Abstract]
Investments	174	281
Derivative contracts, at fair value (asset)	785	182
Assets, Fair Value Disclosure	959	463
Liabilities [Abstract]
Derivative contracts, at fair value (liability)	628	1,224
Other liabilities	214	7
Financial and Nonfinancial Liabilities, Fair Value Disclosure	842	1,231
Recurring measurement \| Level 3
Assets [Abstract]
Investments	41	3
Assets, Fair Value Disclosure	$ 41	3
Liabilities [Abstract]
Other liabilities		6
Financial and Nonfinancial Liabilities, Fair Value Disclosure		$ 6

Investments measured at fair value

No definition available.

Name:	iep_Investmentsmeasuredatfairvalue
Namespace Prefix:	iep_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Unrealized Gain On Derivative Contracts.

+ References

No definition available.

+ Details

Name:	iep_UnrealizedGainOnDerivativeContracts
Namespace Prefix:	iep_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_AssetsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

+ Details

Name:	us-gaap_DerivativeLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of obligations incurred from short sales.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 35
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35711043&loc=d3e42429-110968

+ Details

Name:	us-gaap_FinancialInstrumentsSoldNotYetPurchasedAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LiabilitiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of financial and nonfinancial obligations.

+ References

+ Details

Name:	us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of other liabilities.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherLiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: