Restructuring and Other Charges, Net - Schedule of Restructuring and Other Charges, Net by Reportable Segments, Pretax (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	$ 184	$ 696	$ 1,128
Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	177	55	185
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	7	641	943
Alumina [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	8	(27)	1
Aluminum Segment [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	$ 169	$ 82	$ 184