SEGMENT INFORMATION - Schedule of Segment Revenue Segment Cost and Adjusted EBITDA (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Revenue	$ 7,335	$ 7,826	$ 8,532
Segment adjusted EBITDA	568	754	678
A&T
Segment Reporting Information [Line Items]
Revenue	1,743	1,853	1,728
Cost of metal	(747)	(821)	(886)
Production costs	(618)	(583)	(524)
Other segment expenses	(93)	(98)	(90)
Segment adjusted EBITDA	285	351	228
A&T \| Segment revenue
Segment Reporting Information [Line Items]
Revenue	1,816	1,868	1,786
A&T \| Inter-segment elimination
Segment Reporting Information [Line Items]
Revenue	(73)	(15)	(58)
P&ARP
Segment Reporting Information [Line Items]
Revenue	4,183	4,193	4,891
Cost of metal	(2,890)	(2,839)	(3,623)
Production costs	(946)	(939)	(841)
Other segment expenses	(105)	(110)	(99)
Segment adjusted EBITDA	242	305	328
P&ARP \| Segment revenue
Segment Reporting Information [Line Items]
Revenue	4,196	4,214	4,900
P&ARP \| Inter-segment elimination
Segment Reporting Information [Line Items]
Revenue	(13)	(21)	(9)
AS&I
Segment Reporting Information [Line Items]
Revenue	1,403	1,759	1,913
Cost of metal	(778)	(959)	(1,152)
Production costs	(461)	(572)	(526)
Other segment expenses	(90)	(99)	(92)
Segment adjusted EBITDA	74	129	143
AS&I \| Segment revenue
Segment Reporting Information [Line Items]
Revenue	1,432	1,762	1,955
AS&I \| Inter-segment elimination
Segment Reporting Information [Line Items]
Revenue	(29)	(3)	(42)
H&C
Segment Reporting Information [Line Items]
Revenue	6	21	0
Cost of metal	8	(9)	7
Production costs	(7)	(7)	(2)
Other segment expenses	(40)	(36)	(26)
Segment adjusted EBITDA	(33)	(31)	(21)
H&C \| Segment revenue
Segment Reporting Information [Line Items]
Revenue	6	21	0
H&C \| Inter-segment elimination
Segment Reporting Information [Line Items]
Revenue	$ 0	$ 0	$ 0

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Cost Of Metal

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