Restructuring and Other Charges, Net - Schedule of Restructuring and Other Charges, Net by Reportable Segments, Pretax (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net	$ 652	$ 33	$ 702	$ 73
Operating Segments [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net	(3)	23	45	41
Corporate [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net	655	10	657	32
Bauxite [Member] | Operating Segments [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net			58
Alumina [Member] | Operating Segments [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net	$ (3)		(86)
Aluminum Segment [Member] | Operating Segments [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring and other charges, net		$ 23	$ 73	$ 41