Basis of Presentation and Summary of Significant Accounting Policies Variable Interest Entities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Line Items]
Assets	$ 24,987	$ 24,639
Liabilities	15,730	13,697
Post-retirement benefit liability	81	73
Debt	8,059	8,192
Fair value of long-term debt	8,200	7,600
Portion of inventory under LIFO method	555	869
Accumulated other comprehensive loss	(83)	(82)
Restricted cash	$ 1,592	1,151
Aggregate general partner ownership interest of parent and operating subsidiary	1.99%
Icahn Enterprises G.P.
Accounting Policies [Line Items]
Affiliate ownership interest	98.01%
Aggregate general partner ownership interest of parent and operating subsidiary	1.99%
Icahn Enterprises Holdings
Accounting Policies [Line Items]
Percentage of equity ownership in operating subsidiary	99.00%
Affiliate ownership interest	99.00%
Aggregate general partner ownership interest of parent and operating subsidiary	1.00%
Icahn Enterprises Holdings LP
Accounting Policies [Line Items]
Affiliate ownership interest	98.01%
Cash held at consolidated affiliated partnerships [Member]
Accounting Policies [Line Items]
Restricted cash	$ 686	86
Restricted cash
Accounting Policies [Line Items]
Restricted cash	$ 906	1,065
Variable Interest Entity, Primary Beneficiary | Viskase
Accounting Policies [Line Items]
Percentage of equity ownership in operating subsidiary	50.00%
Real Estate Segment
Accounting Policies [Line Items]
Assets	$ 486	514
Liabilities	46	40
Debt	1	2
Restricted cash	$ 8	2
Real Estate Segment | Minimum
Accounting Policies [Line Items]
Lessee term	5 years
Real Estate Segment | Maximum
Accounting Policies [Line Items]
Lessee term	39 years
Food Packaging Segment
Accounting Policies [Line Items]
Assets	$ 485	517
Liabilities	332	464
Debt	$ 151	268
Restricted cash		$ 1
Lessee term	11 years 1 month 6 days	11 years 8 months 12 days
Food Packaging Segment | Viskase
Accounting Policies [Line Items]
Percentage of equity ownership in operating subsidiary	79.00%	75.00%
Energy Segment
Accounting Policies [Line Items]
Assets	$ 4,723	$ 4,673
Liabilities	2,880	2,375
Deferred revenue	31	28
Recorded revenue	27	68	$ 34
Debt	1,691	$ 1,195
Restricted cash	$ 7
Lessee term	3 years 1 month 6 days	3 years 8 months 12 days
Remaining performance obligation expected to be recognized as revenue within one year	$ 3
Remaining performance obligation for contracts with an original expected duration of more than one year	$ 6
Energy Segment | Minimum | Refineries
Accounting Policies [Line Items]
Turnaround Term of Plants	4 years
Energy Segment | Minimum | Nitrogen Fertilizer Plants
Accounting Policies [Line Items]
Turnaround Term of Plants	2 years
Energy Segment | Maximum | Refineries
Accounting Policies [Line Items]
Turnaround Term of Plants	5 years
Energy Segment | Maximum | Nitrogen Fertilizer Plants
Accounting Policies [Line Items]
Turnaround Term of Plants	3 years
Automotive Segment
Accounting Policies [Line Items]
Assets	$ 3,089	$ 3,495
Liabilities	1,535	1,745
Deferred revenue	41	42
Recorded revenue	25	21	$ 18
Debt	$ 368	$ 405
Lessee term	4 years 7 months 6 days	5 years 2 months 12 days
Icahn Enterprises Holdings
Accounting Policies [Line Items]
Assets	$ 24,987	$ 24,639
Liabilities	15,732	13,700
Debt	8,061	8,195
Restricted cash	1,592	1,151
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Cash and cash equivalents
Accounting Policies [Line Items]
Assets	31	42
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Cash held at consolidated affiliated partnerships and restricted cash
Accounting Policies [Line Items]
Assets	1,558	989
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Investments [Member]
Accounting Policies [Line Items]
Assets	8,239	9,207
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Due from brokers
Accounting Policies [Line Items]
Assets	3,437	858
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Accounts receivable, net
Accounting Policies [Line Items]
Assets	37	35
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Inventories, net
Accounting Policies [Line Items]
Assets	42	48
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Property, plant and equipment
Accounting Policies [Line Items]
Assets	1,042	1,110
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Unrealized gain on derivative contracts
Accounting Policies [Line Items]
Assets	785	182
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Intangible assets, net
Accounting Policies [Line Items]
Assets	232	251
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Other assets [Member]
Accounting Policies [Line Items]
Assets	107	49
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Accounts payable
Accounting Policies [Line Items]
Liabilities	25	25
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Accrued expenses and other liabilities
Accounting Policies [Line Items]
Liabilities	70	97
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Deferred tax liability [Member]
Accounting Policies [Line Items]
Liabilities	1	1
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Unrealized loss on derivative contracts
Accounting Policies [Line Items]
Liabilities	622	1,215
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Securities sold, not yet purchased
Accounting Policies [Line Items]
Liabilities	2,521	1,190
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Due to brokers
Accounting Policies [Line Items]
Liabilities	1,618	54
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary | Debt
Accounting Policies [Line Items]
Liabilities	$ 636	$ 633