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, 2021	Dec. 31, 2020	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 1,128	$ 104	$ 1,031
Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	185	59	888
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	943	45	143
Bauxite [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		1	5
Alumina [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	1	5	272
Aluminum Segment [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 184	$ 53	$ 611