SEGMENT REPORTING - Segment Assets (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Total assets	$ 18,652	$ 18,755
Corporate/Eliminations
Segment Reporting Information [Line Items]
Total assets	322	370
Operating Segments
Segment Reporting Information [Line Items]
Total assets	18,330	18,385
Operating Segments | Steelmaking
Segment Reporting Information [Line Items]
Total assets	18,018	18,070
Operating Segments | Other Businesses
Segment Reporting Information [Line Items]
Total assets	$ 312	$ 315