Segment and Related Information - Schedule of Third-party Sales by Product Division (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation Of Revenue [Line Items]
Sales	$ 12,451	$ 12,152	$ 9,286
Primary Aluminum [Member]
Disaggregation Of Revenue [Line Items]
Sales	8,887	8,420	5,190
Alumina [Member]
Disaggregation Of Revenue [Line Items]
Sales	3,478	3,125	2,624
Flat-Rolled Aluminum [Member]
Disaggregation Of Revenue [Line Items]
Sales		320	1,115
Energy [Member]
Disaggregation Of Revenue [Line Items]
Sales	201	286	141
Bauxite [Member]
Disaggregation Of Revenue [Line Items]
Sales	168	207	238
Other Products [Member]
Disaggregation Of Revenue [Line Items]
Sales	$ (283)	$ (206)	$ (22)