Accumulated Other Comprehensive Loss - Summary of Changes in Accumulated Other Comprehensive (Loss) Income by Component (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Settlements and/or curtailments related to retirement benefits	$ 21	$ 632	$ 977
Net amount reclassified to earnings	130	316
Cost of Goods Sold [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net amount reclassified to earnings	5	5
Sales [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net amount reclassified to earnings	31	10
Alcoa Corporation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Settlements and/or curtailments related to retirement benefits	21	633	952
Net amount reclassified to earnings	130	316	295
Non-controlling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Settlements and/or curtailments related to retirement benefits	0	$ (1)	25
Net amount reclassified to earnings	$ (1)		$ 2