Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

ACQUISITIONS - Narrative (Details) $ in Millions			3 Months Ended
ACQUISITIONS - Narrative (Details) $ in Millions	Dec. 09, 2020 USD ($)	Mar. 13, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)
Business Acquisition [Line Items]
Acquisition-related costs			$ 13	$ 42
ArcelorMittal USA
Business Acquisition [Line Items]
Acquisition-related costs			$ 2
Consideration transferred	$ 2,600
AK Steel
Business Acquisition [Line Items]
Exchange ratio		0.400
Consideration transferred		$ 1,535