Basis of Presentation and Summary of Significant Accounting Policies Variable Interest Entities (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($) numberOfLeases	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) numberOfLeases	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)
Accounting Policies [Line Items]
Post-retirement benefit liability	$ 73				$ 77				$ 73	$ 77
Operating lease liability	647								647
Finance Lease, Liability	93								93
Cash and cash equivalents	3,794				2,656				3,794	2,656
Cash held at consolidated affiliated partnerships and restricted cash	1,151				2,682				1,151	2,682
Investments	9,945				8,337				9,945	8,337
Due from brokers	858				664				858	664
Inventories, net	1,812				1,779				1,812	1,779
Property, plant and equipment, net	4,541				4,688				4,541	4,688
Intangible assets, net	431				501				431	501
Other assets	1,350				1,461				1,350	1,461
Accounts payable, accrued expenses and other liabilities	4,315				2,715				4,315	2,715
Securities sold, not yet purchased, at fair value	1,190				468				1,190	468
Due to brokers	54				141				54	141
Debt	8,192				7,326				8,192	7,326
Fair value of long-term debt	7,700				7,300				7,700	7,300
Portion of inventory under LIFO method	869				846				869	846
Accumulated other comprehensive loss	(89)				(85)				$ (89)	(85)
Affiliate ownership interest									98.01%
Total revenues	2,621	$ 2,320	$ 2,196	$ 1,855	2,802	$ 2,569	$ 3,423	$ 2,983	$ 8,992	11,777	$ 12,619
Cost of goods sold									8,212	9,002	8,220
Total Expenses									10,731	11,554	10,753
Income (loss) before income tax benefit									(1,739)	223	1,866
Income tax (expense) benefit									20	(14)	(532)
Income (loss) from continuing operations	(149)	(373)	(573)	(664)	(206)	(334)	410	367	(1,759)	237	2,398
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest									(693)	475	101
Continuing operations									(1,066)	(238)	2,297
Net income (loss) attributable to Icahn Enterprises	(157)	$ (49)	$ (498)	$ (394)	930	$ 118	$ 302	$ 132	(1,098)	1,482	2,454
Other expenses from operations										2,552	2,533
Other assets
Accounting Policies [Line Items]
Operating lease right-of-use asset	622				0				622	0
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					108					108
Property, plant and equipment
Accounting Policies [Line Items]
Finance lease right-of-use asset	77				41				$ 77	41
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					(15)					(15)
Deferred tax liability [Member]
Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					18					18
Stockholders' Equity, Total [Member]
Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					75					75
Equity attributable to Icahn Enterprises [Member]
Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					31					31
Restatement Adjustment
Accounting Policies [Line Items]
Total revenues										0	0
Cost of goods sold										55	(38)
Total Expenses										55	(38)
Income (loss) before income tax benefit										(55)	38
Income tax (expense) benefit										(10)	(3)
Income (loss) from continuing operations										(45)	41
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest										(20)	17
Continuing operations										(25)	24
Net income (loss) attributable to Icahn Enterprises										(25)	24
Other expenses from operations										0	0
Previously Reported [Member]
Accounting Policies [Line Items]
Total revenues										11,777	12,619
Cost of goods sold										8,947	8,258
Total Expenses										11,499	10,791
Income (loss) before income tax benefit										278	1,828
Income tax (expense) benefit										(4)	(529)
Income (loss) from continuing operations										282	2,357
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest										495	84
Continuing operations										(213)	2,273
Net income (loss) attributable to Icahn Enterprises										1,507	2,430
Other expenses from operations										2,552	2,533
Icahn Enterprises G.P.
Accounting Policies [Line Items]
Aggregate general partner ownership interest of parent and operating subsidiary									1.99%
Cash held at consolidated affiliated partnerships [Member]
Accounting Policies [Line Items]
Cash held at consolidated affiliated partnerships and restricted cash	86				2,648				$ 86	2,648
Restricted cash
Accounting Policies [Line Items]
Cash held at consolidated affiliated partnerships and restricted cash	1,065				34				1,065	34
Real Estate Segment
Accounting Policies [Line Items]
Cash and cash equivalents	53				39				53	39
Cash held at consolidated affiliated partnerships and restricted cash	2				26				2	26
Investments	15				15				15	15
Inventories, net	0				0				0	0
Property, plant and equipment, net	386				367				386	367
Accounts payable, accrued expenses and other liabilities	38				41				38	41
Securities sold, not yet purchased, at fair value	0				0				0	0
Debt	2				2				2	2
Total revenues									103	212	628
Cost of goods sold									18	18	11
Total Expenses									93	95	79
Income (loss) before income tax benefit									10	117	549
Income tax (expense) benefit									(6)	5	0
Income (loss) from continuing operations									16	112	549
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest									0	0	0
Continuing operations									$ 16	112	549
Real Estate Segment | Minimum
Accounting Policies [Line Items]
Description of Lessor Leasing Arrangements, Operating Leases									5 years
Real Estate Segment | Maximum
Accounting Policies [Line Items]
Description of Lessor Leasing Arrangements, Operating Leases									39 years
Food Packaging Segment
Accounting Policies [Line Items]
Operating lease right-of-use asset												$ 35
Operating lease liability												39
Cash and cash equivalents	22				46				$ 22	46
Cash held at consolidated affiliated partnerships and restricted cash	1				1				1	1
Investments	0				0				0	0
Inventories, net	100				93				100	93
Property, plant and equipment, net	161				169				161	169
Accounts payable, accrued expenses and other liabilities	196				164				196	164
Securities sold, not yet purchased, at fair value	0				0				0	0
Debt	268				273				268	273
Total revenues									375	379	389
Cost of goods sold									309	316	297
Total Expenses									391	398	374
Income (loss) before income tax benefit									(16)	(19)	15
Income tax (expense) benefit									6	(4)	21
Income (loss) from continuing operations									(22)	(15)	(6)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest									(5)	(3)	(1)
Continuing operations									(17)	(12)	(5)
Food Packaging Segment | Other assets
Accounting Policies [Line Items]
Operating lease right-of-use asset	34								34
Other Segments and Holding Company
Accounting Policies [Line Items]
Operating lease right-of-use asset												34
Operating lease liability												28
Investments	738				1,470				738	1,470
Other Segments and Holding Company | Other assets
Accounting Policies [Line Items]
Operating lease right-of-use asset	39								39
Energy Segment
Accounting Policies [Line Items]
Deferred revenue	28				69				28	69
Revenue recognition during period of previously deferred revenue									68	34
Finance lease right-of-use asset												26
Operating lease right-of-use asset												56
Operating lease liability												56
Finance Lease, Liability												23
Cash and cash equivalents	652				668				652	668
Cash held at consolidated affiliated partnerships and restricted cash	0				0				0	0
Investments	81				84				81	84
Inventories, net	390				380				390	380
Property, plant and equipment, net	2,888				3,027				2,888	3,027
Accounts payable, accrued expenses and other liabilities	1,180				1,043				1,180	1,043
Securities sold, not yet purchased, at fair value	0				0				0	0
Debt	1,195				1,170				1,195	1,170
Remaining performance obligation expected to be recognized as revenue within one year	4								4
Remaining performance obligation for contracts with an original expected duration of more than one year	9								9
Total revenues									6,385	7,135	5,988
Cost of goods sold									5,707	6,508	5,761
Total Expenses									5,959	6,755	6,013
Income (loss) before income tax benefit									426	380	(25)
Income tax (expense) benefit									112	46	(341)
Income (loss) from continuing operations									314	334	316
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest									68	121	63
Continuing operations									246	213	253
Energy Segment | Other assets
Accounting Policies [Line Items]
Operating lease right-of-use asset	48								48
Automotive Segment
Accounting Policies [Line Items]
Deferred revenue	$ 42				42				42	42
Revenue recognition during period of previously deferred revenue									$ 21	18
Number of leases | numberOfLeases	2,300								2,300
Finance lease right-of-use asset												20
Operating lease right-of-use asset												589
Operating lease liability												621
Finance Lease, Liability												$ 22
Cash and cash equivalents	$ 46				43				$ 46	43
Cash held at consolidated affiliated partnerships and restricted cash	0				0				0	0
Investments	120				59				120	59
Inventories, net	1,215				1,203				1,215	1,203
Property, plant and equipment, net	916				941				916	941
Accounts payable, accrued expenses and other liabilities	1,340				905				1,340	905
Securities sold, not yet purchased, at fair value	0				0				0	0
Debt	405				372				405	372
Deferred revenue expected to be earned within one year	21								21
Total revenues									2,895	2,856	2,728
Cost of goods sold									1,625	1,502	1,540
Total Expenses									3,147	3,138	2,925
Income (loss) before income tax benefit									(252)	(282)	(197)
Income tax (expense) benefit									(55)	(52)	(146)
Income (loss) from continuing operations									(197)	(230)	(51)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest									0	0	0
Continuing operations									(197)	(230)	(51)
Automotive Segment | Other assets
Accounting Policies [Line Items]
Operating lease right-of-use asset	501								$ 501
Icahn Enterprises Holdings
Accounting Policies [Line Items]
Percentage of equity ownership in operating subsidiary									99.00%
Percentage of equity ownership in subsidiary									99.00%
Cash and cash equivalents	3,794				2,656				$ 3,794	2,656
Cash held at consolidated affiliated partnerships and restricted cash	1,151				2,682				1,151	2,682
Investments	9,945				8,337				9,945	8,337
Due from brokers	858				664				858	664
Inventories, net	1,812				1,779				1,812	1,779
Property, plant and equipment, net	4,541				4,688				4,541	4,688
Intangible assets, net	431				501				431	501
Other assets	1,350				1,493				1,350	1,493
Securities sold, not yet purchased, at fair value	1,190				468				1,190	468
Due to brokers	54				141				54	141
Debt	8,195				7,330				8,195	7,330
Total revenues									8,992	11,777	12,619
Cost of goods sold									8,212	9,002	8,220
Total Expenses									10,730	11,553	10,751
Income (loss) before income tax benefit									(1,738)	224	1,868
Income tax (expense) benefit									20	(14)	(532)
Income (loss) from continuing operations									(1,758)	238	2,400
Continuing operations									(1,065)	(237)	2,299
Net income (loss) attributable to Icahn Enterprises									(1,097)	1,483	$ 2,456
Icahn Enterprises Holdings | Variable Interest Entity, Primary Beneficiary
Accounting Policies [Line Items]
Cash and cash equivalents	42				420				42	420
Cash held at consolidated affiliated partnerships and restricted cash	989				2,648				989	2,648
Investments	9,207				6,951				9,207	6,951
Due from brokers	858				664				858	664
Inventories, net	54				380				54	380
Property, plant and equipment, net	1,123				3,023				1,123	3,023
Intangible assets, net	258				278				258	278
Other assets	260				932				260	932
Accounts payable, accrued expenses and other liabilities	1,338				523				1,338	523
Securities sold, not yet purchased, at fair value	1,190				468				1,190	468
Due to brokers	54				141				54	141
Debt	$ 633				$ 1,171				$ 633	$ 1,171
Viskase
Accounting Policies [Line Items]
Subsidiary ownership interest in variable interest entity									50.00%
Viskase | Food Packaging Segment
Accounting Policies [Line Items]
Percentage of equity ownership in operating subsidiary									78.60%	74.60%
Percentage of equity ownership in subsidiary									78.60%	74.60%