Annual report pursuant to Section 13 and 15(d)

SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION - Non-cash Investing and Financing Activities (Details)

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SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION - Non-cash Investing and Financing Activities (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Ferrous Processing and Trading      
Noncash or Part Noncash Acquisitions [Line Items]      
Fair value of settlement of a pre-existing relationship as part of consideration in connection with transaction $ (20) $ 0 $ 0
ArcelorMittal USA      
Noncash or Part Noncash Acquisitions [Line Items]      
Fair value of settlement of a pre-existing relationship as part of consideration in connection with transaction 0 (237) 0
ArcelorMittal USA | Common Stock      
Noncash or Part Noncash Acquisitions [Line Items]      
Fair value of other consideration given 0 990 0
ArcelorMittal USA | Series B Preferred Stock      
Noncash or Part Noncash Acquisitions [Line Items]      
Fair value of other consideration given 0 738 0
AK Steel | Common Stock      
Noncash or Part Noncash Acquisitions [Line Items]      
Fair value of other consideration given 0 618 0
Share-based Payment Arrangement | AK Steel      
Noncash or Part Noncash Acquisitions [Line Items]      
Fair value of other consideration given $ 0 $ 4 $ 0