Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Consolidation, Policy	Principles of Consolidation As of September 30, 2018, our condensed consolidated financial statements include the accounts of (i) Icahn Enterprises and Icahn Enterprises Holdings and (ii) the wholly and majority owned subsidiaries of Icahn Enterprises and Icahn Enterprises Holdings, in addition to variable interest entities ("VIEs") in which we are the primary beneficiary. In evaluating whether we have a controlling financial interest in entities that we consolidate, we consider the following: (1) for voting interest entities, including limited partnerships and similar entities that are not VIEs, we consolidate these entities in which we own a majority of the voting interests; and (2) for VIEs, we consolidate these entities in which we are the primary beneficiary. See below for a discussion of our VIEs. Kick-out rights, which are the rights underlying the limited partners' ability to dissolve the limited partnership or otherwise remove the general partners, held through voting interests of partnerships and similar entities that are not VIEs are considered the equivalent of the equity interests of corporations that are not VIEs. Except for our Investment segment, for equity investments in which we own 50% or less but greater than 20%, we generally account for such investments using the equity method. All other equity investments are accounted for at fair value.
Fair Value of Financial Instruments, Policy	Fair Value of Financial Instruments The carrying values of cash and cash equivalents, cash held at consolidated affiliated partnerships and restricted cash, accounts receivable, due from brokers, accounts payable, accrued expenses and other liabilities and due to brokers are deemed to be reasonable estimates of their fair values because of their short-term nature. See Note 4, “Investments and Related Matters,” and Note 5, “Fair Value Measurements,” for a detailed discussion of our investments and other non-financial assets and/or liabilities.
New Accounting Pronouncements	Adoption of New Accounting Standards Revenue Accounting Standards Updates In May 2014, the FASB issued ASU No. 2014-09, creating a new topic, FASB ASC Topic 606, Revenue from Contracts with Customers, superseding revenue recognition requirements in FASB ASC Topic 605, Revenue Recognition. This ASU requires that an entity recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. In addition, an entity is required to disclose sufficient information to enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. This ASU was amended by ASU No. 2015-14, issued in August 2015, which deferred the original effective date by one year; the effective date of this ASU is for fiscal years, and interim reporting periods within those years, beginning after December 15, 2017, using one of two retrospective application methods. In addition, the FASB issued other amendments during 2016 and 2017 to FASB ASC Topic 606 that include implementation guidance to principal versus agent considerations, guidance to identifying performance obligations and licensing guidance and other narrow scope improvements. We adopted these new standards on January 1, 2018 using the modified retrospective application method which required a cumulative effect adjustment recognized in equity at such date. The standard has been applied to all contracts at the date of initial application. No adjustment to revenue for periods prior to adoption were required. We have not identified any material differences in our revenue recognition methods that required modification under the new standards. Additionally, our internal control framework did not materially change as a result of the adoption of these new standards. The impact of adopting these new standards on our condensed consolidated financial statements is a cumulative effect adjustment to decrease our equity attributable to Icahn Enterprises and Icahn Enterprises Holdings as of January 1, 2018 by $29 million, primarily relating to our Automotive segment. As of January 1, 2018, our Automotive segment increased accrued expenses and other liabilities by $42 million and decreased deferred tax liabilities by $10 million for certain extended warranties to reflect the revenues from these plans as deferred revenue. Previously, revenues from these plans were recognized upfront. Our Automotive segment also recognizes revenue from the sale of goods on a drop ship basis. Previously, revenues from these transactions were recognized gross. For the three months ended September 30, 2018, net sales and costs of goods sold would have been higher by $15 million and $15 million, respectively, under prior accounting principles and for the nine months ended September 30, 2018, net sales and cost of goods sold would have been higher by $47 million and $47 million, respectively. As of January 1, 2018, our Energy segment increased each of accounts receivable, net and accrued expenses and other liabilities by $21 million for customer prepayments prior to delivery and to gross up certain fees collected from customers to reflect a receivable and deferred revenue recorded at the point in time in which a prepaid contract is legally enforceable and the associated right to consideration is unconditional. Previously, deferred revenue was recorded by our Energy segment upon customer prepayment. In addition to the above, we increased assets by an aggregate of $32 million and increased liabilities by $29 million as of January 1, 2018, primarily with respect to Federal-Mogul's asset and liabilities classified as held for sale. For the three and nine months ended September 30, 2018, the impact on revenues would have been immaterial under prior accounting principles. Other Accounting Standards Updates In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall, which amends FASB ASC Topic 825, Financial Instruments. This ASU requires that equity investments (except those accounted for under the equity method of accounting or those that result in the consolidation of the investee) to be measured at fair value with changes recognized in earnings. However, an entity may choose to measure equity investments that do not have readily determinable fair values at cost minus impairment. In addition, there were other amendments to certain disclosure and presentation matters pertaining to financial instruments, including the requirement of an entity to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes. This ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We adopted this new standard on January 1, 2018 using the modified retrospective application method which required a cumulative effect adjustment recognized in equity at such date. The amendments related to equity securities without readily determinable fair values were applied prospectively to equity investments that existed as of the date of adoption. The adoption of this standard did not have a material impact on our condensed consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments, which amends FASB ASC Topic 230, Statement of Cash Flows. This ASU seeks to reduce the diversity currently in practice by providing guidance on the presentation of eight specific cash flow issues in the statement of cash flows. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We adopted this standard on January 1, 2018 using the retrospective application method. The adoption of this standard did not have a material impact on our condensed consolidated statements of cash flows. In November 2016, the FASB issued ASU No. 2016-18, Restricted Cash, which amends FASB ASC Topic 230, Statement of Cash Flows. This ASU requires that the statement of cash flows explain the change during the period total cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We have adopted this standard on January 1, 2018 using the retrospective application method. The impact of adopting this new standard is discussed above under "Reclassifications." In March 2017, the FASB issued ASU No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, which amends FASB ASC Topic 715, Compensation - Retirement Benefits. This ASU requires entities to present the service cost component of net periodic benefit cost in the same line item or items in the financial statements as other compensation costs arising from services rendered by the pertinent employees during the period. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We adopted this standard on January 1, 2018 using the retrospective application method. The impact of adopting this new standard is discussed above under "Reclassifications." In May 2017, the FASB issued ASU No. 2017-09, Scope of Modification Accounting, which amends FASB ASC Topic 718, Compensation - Stock Compensation. This ASU provides updated guidance about which changes to the terms and conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. We adopted this standard on January 1, 2018 which has been applied prospectively and which did not have a material impact on our condensed consolidated financial statements.
Description of New Accounting Pronouncements Not yet Adopted	Recently Issued Accounting Standards In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which supersedes FASB ASC Topic 840, Leases. This ASU requires the recognition of right-of-use assets and lease liabilities by lessees for those leases classified as operating leases under previous guidance. In addition, among other changes to the accounting for leases, this ASU retains the distinction between finance leases and operating leases. The classification criteria for distinguishing between finance leases and operating leases are substantially similar to the classification criteria for distinguishing between capital leases and operating leases in the previous guidance. Furthermore, quantification and qualitative disclosures, including disclosures regarding significant judgments made by management, will be required. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The amendments in this ASU should be applied using a modified retrospective approach. Early application is permitted. In addition, in July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842), which provides an additional (and optional) transition method to adopt the new leases standard. We anticipate adopting the new leases standard using the new transition method option effective January 1, 2019, which will require adopting the new leases standard at the adoption date and recognizing a cumulative-effect adjustment to the opening balance of equity in the period of adoption instead of the earliest period presented. In addition, prior period presentation and disclosure will not be adjusted. We believe the most significant impact will relate to the recognition of right-of-use assets and lease liabilities on our condensed consolidated balance sheets for long-term operating leases with the significant majority of the impact within our Automotive segment. We anticipate our assessment and implementation plan to be ongoing during the remainder of 2018 and continue to evaluate the impact of this standard on our condensed consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments, which amends FASB ASC Topic 326, Financial Instruments - Credit Losses. This ASU requires financial assets measured at amortized cost to be presented at the net amount to be collected and broadens the information, including forecasted information incorporating more timely information, that an entity must consider in developing its expected credit loss estimate for assets measured. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early application is permitted for fiscal years beginning after December 15, 2018. We are currently evaluating the impact of this standard on our condensed consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, Targeting Improvements to Accounting for Hedging Activities, which amends FASB ASC Topic 815, Derivatives and Hedging. This ASU includes amendments to existing guidance to better align an entity’s risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. This ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the impact of this standard on our condensed consolidated financial statements. In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, which amends FASB ASC Topic 220, Income Statement - Reporting Comprehensive Income. This ASU allows a reclassification out of accumulated other comprehensive loss within equity for standard tax effects resulting from the Tax Cuts and Jobs Act and consequently, eliminates the stranded tax effects resulting from the Tax Cuts and Jobs Act. This ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. We are currently evaluating the impact of this standard on our condensed consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurements, which amends FASB ASC Topic 820, Fair Value Measurements. This ASU eliminates, modifies and adds various disclosure requirements on fair value measurements. This ASU is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Certain disclosures are required to be applied using a retrospective approach and others using a prospective approach. Early adoption is permitted. We are currently evaluating the impact of this standard on our condensed consolidated financial statements. In August 2018, the FASB issued ASU 2018-15, Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract, which amends FASB ASC Subtopic 350-40, Intangibles-Goodwill and Other-Internal-Use Software. This ASU adds certain disclosure requirements related to implementation costs incurred for internal-use software and cloud computing arrangements. The amendment aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This ASU is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The amendments in this ASU should be applied either using a retrospective or prospective approach. Early adoption is permitted. We are currently evaluating the impact of this standard on our condensed consolidated financial statements.
Automotive Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Revenue Recognition, Policy	Revenue: Our Automotive segment recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. Our Automotive segment revenue from retail and commercial sales is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. Automotive service revenues are recognized on completion of the service and consist of products and the labor charged for installing products or maintaining or repairing vehicles. Automotive services labor revenues are included in other revenues from operations in our condensed consolidated statements of operations, however, the sale of any installed parts or materials related to automotive services are included in net sales. Our Automotive segment recognizes revenues from extended warranties offered to its customers on tires its sells, including lifetime warranties for road hazard assistance (recognized over 3 years) and 1-year, 3-year and lifetime plans for alignments (recognized over 1 year, 3 years and 5 years, respectively), for which it receives payment upfront. Revenues from extended warranties are recognized over the term of the warranty contract with the satisfaction of its performance obligations measured using the output method. Our Automotive segment recognizes revenues from franchise fees, which it receives payment upfront, and franchise royalties, for which it receives payment over time. Revenues from upfront franchise fees are recognized at the time the store opens, as that is when our Automotive segment's performance obligations are deemed complete, and revenues from franchise royalties are recognized in the period in which royalties are earned, generally based on a percentage of franchise sales.
Energy Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Revenue Recognition, Policy	Revenue: Our Energy segment revenues from the sale of petroleum products are recorded upon delivery of the products to customers, which is the point at which title is transferred and the customer has assumed the risk of loss. This generally takes place as product passes into the pipeline, as a product transfer order occurs within a pipeline system, or as product enters equipment or locations supplied or designated by the customer. For our Energy segment's nitrogen fertilizer products sold, revenues are recorded at the point in time at which the customer obtains control of the product, which is generally upon delivery and acceptance by the customer. Nitrogen fertilizer products are sold on a wholesale basis under a contract or by purchase order. Excise and other taxes collected from customers and remitted to governmental authorities by our Energy segment are not included in reported revenues. Many of the petroleum business' contracts have index-based pricing which is considered variable consideration that should be estimated in determining the transaction price. Our Energy segment determined that it does not need to estimate the variable consideration because the uncertainty related to the consideration is resolved on the pricing date or the date when the product is delivered. The nitrogen fertilizer business has an immaterial amount of variable consideration for contracts with an original duration of less than a year. A small portion of the nitrogen fertilizer partnership's revenue includes contracts extending beyond one year and contain variable pricing in which the majority of the variability is attributed to the market-based pricing. The nitrogen fertilizer business' contracts do not contain a significant financing component.
Railcar Segment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Revenue Recognition, Policy	Revenue: Revenues from manufactured railcar sales are recognized following completion of manufacturing, inspection, customer acceptance and title transfer, which is when the risk for any damage or loss with respect to the railcars passes to the customer, in accordance with our Railcar segment's contractual terms. Revenues from railcar and industrial components are recorded at the time of product shipment, in accordance with our Railcar segment's contractual terms. Revenues from railcar maintenance services are recognized upon completion and shipment of railcars from our Railcar segment's plants. Our Railcar segment does not currently bundle railcar service contracts with new railcar sales. Revenues from engineering and field services are recognized as performed. As of September 30, 2018, our Railcar segment had $963 million of remaining performance obligations for contractual commitments from customers for which work is partially completed. Our Railcar segment expects to recognize approximately $184 million of these performance obligations as revenue during the next twelve months and an additional $779 million thereafter.