Segment Reporting - Condensed Balance Sheets By Reporting Segment (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
ASSETS
Cash and cash equivalents	$ 1,945			$ 1,679
Cash held at consolidated affiliated partnerships and restricted cash	1,747			1,612
Investments	9,897			8,913
Accounts receivable, net	598			501
Inventories, net	1,590			1,580
Property, plant and equipment, net	4,194			4,228
Goodwill and intangible assets, net	907			954
Other assets	7,095			5,522
Assets	27,973			24,989
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	5,297			5,151
Securities sold, not yet purchased, at fair value	4,957			2,521
Debt	7,712			8,059
Total liabilities	17,966			15,731
Equity attributable to Icahn Enterprises	3,770			3,383
Equity attributable to non-controlling interests	6,237			5,875
Total equity	10,007	$ 10,025	$ 9,582	9,258	$ 8,873	$ 10,265	$ 9,417	$ 10,942
Total liabilities and equity	27,973			24,989
Investment Segment
ASSETS
Cash and cash equivalents	19			14
Cash held at consolidated affiliated partnerships and restricted cash	1,636			1,558
Investments	9,653			8,239
Other assets	5,988			4,308
Assets	17,296			14,119
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	2,107			2,256
Securities sold, not yet purchased, at fair value	4,957			2,521
Total liabilities	7,064			4,777
Equity attributable to Icahn Enterprises	4,660			4,283
Equity attributable to non-controlling interests	5,572			5,059
Total equity	10,232			9,342
Total liabilities and equity	17,296			14,119
Energy Segment
ASSETS
Cash and cash equivalents	566			667
Cash held at consolidated affiliated partnerships and restricted cash	7			7
Investments	83			253
Accounts receivable, net	240			178
Inventories, net	422			298
Property, plant and equipment, net	2,765			2,747
Goodwill and intangible assets, net	225			238
Other assets	261			335
Assets	4,569			4,723
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	1,540			1,189
Debt	1,676			1,691
Total liabilities	3,216			2,880
Equity attributable to Icahn Enterprises	701			1,039
Equity attributable to non-controlling interests	652			804
Total equity	1,353			1,843
Total liabilities and equity	4,569			4,723
Automotive Segment
ASSETS
Cash and cash equivalents	48			25
Cash held at consolidated affiliated partnerships and restricted cash	19			20
Investments	12			40
Accounts receivable, net	112			109
Inventories, net	928			1,080
Property, plant and equipment, net	830			857
Goodwill and intangible assets, net	364			372
Other assets	554			582
Assets	2,867			3,085
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	1,036			1,163
Debt	16			368
Total liabilities	1,052			1,531
Equity attributable to Icahn Enterprises	1,815			1,554
Total equity	1,815			1,554
Total liabilities and equity	2,867			3,085
Food Packaging Segment
ASSETS
Cash and cash equivalents	10			16
Accounts receivable, net	88			88
Inventories, net	95			89
Property, plant and equipment, net	145			160
Goodwill and intangible assets, net	28			31
Other assets	100			103
Assets	466			487
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	159			182
Debt	154			151
Total liabilities	313			333
Equity attributable to Icahn Enterprises	140			142
Equity attributable to non-controlling interests	13			12
Total equity	153			154
Total liabilities and equity	466			487
Metals Segment
ASSETS
Cash and cash equivalents				1
Cash held at consolidated affiliated partnerships and restricted cash	1			2
Accounts receivable, net	90			63
Inventories, net	37			22
Property, plant and equipment, net	77			82
Goodwill and intangible assets, net	8			9
Other assets	25			38
Assets	238			217
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	73			73
Debt	18			16
Total liabilities	91			89
Equity attributable to Icahn Enterprises	147			128
Total equity	147			128
Total liabilities and equity	238			217
Real Estate Segment
ASSETS
Cash and cash equivalents	30			21
Cash held at consolidated affiliated partnerships and restricted cash	9			8
Investments	15			15
Accounts receivable, net	12			10
Property, plant and equipment, net	309			310
Goodwill and intangible assets, net				1
Other assets	108			121
Assets	483			486
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	45			45
Debt	2			1
Total liabilities	47			46
Equity attributable to Icahn Enterprises	436			440
Total equity	436			440
Total liabilities and equity	483			486
Home Fashion Segment
ASSETS
Cash and cash equivalents	4			2
Cash held at consolidated affiliated partnerships and restricted cash				6
Accounts receivable, net	35			33
Inventories, net	95			81
Property, plant and equipment, net	62			65
Goodwill and intangible assets, net	21			21
Other assets	16			19
Assets	233			227
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	65			65
Debt	36			21
Total liabilities	101			86
Equity attributable to Icahn Enterprises	132			141
Total equity	132			141
Total liabilities and equity	233			227
Pharma Segment
ASSETS
Cash and cash equivalents	11			8
Accounts receivable, net	21			20
Inventories, net	13			10
Goodwill and intangible assets, net	261			282
Other assets	7			6
Assets	313			326
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	50			64
Total liabilities	50			64
Equity attributable to Icahn Enterprises	263			262
Total equity	263			262
Total liabilities and equity	313			326
Holding Company
ASSETS
Cash and cash equivalents	1,257			925
Cash held at consolidated affiliated partnerships and restricted cash	75			11
Investments	134			366
Property, plant and equipment, net	6			7
Other assets	36			10
Assets	1,508			1,319
LIABILITIES AND EQUITY
Accounts payable, accrued expenses and other liabilities	222			114
Debt	5,810			5,811
Total liabilities	6,032			5,925
Equity attributable to Icahn Enterprises	(4,524)			(4,606)
Total equity	(4,524)			(4,606)
Total liabilities and equity	$ 1,508			$ 1,319