Income Taxes - Additional Information (Detail) $ in Millions, $ in Millions		1 Months Ended		3 Months Ended		12 Months Ended
	Aug. 16, 2022	Dec. 31, 2022 USD ($) LegalEntity	Oct. 30, 2022 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2020 AUD ($)	Dec. 31, 2024 USD ($) Filer	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2024 AUD ($)	Aug. 01, 2024 USD ($)	Dec. 31, 2023 AUD ($)	Dec. 31, 2021 USD ($)
Income Taxes [Line Items]
Corporate income tax rate						21.00%	21.00%	21.00%
Tax expense (benefit)						$ 265	$ 189	$ 664
Deferred income taxes (Q)						23	(22)	219
Deferred income taxes						284
Deferred tax liability						405
Deferred tax asset						689	645			$ 121
Deferred tax asset, fixed asset valuation						95
Deferred tax asset related to capital loss carryforwards						265
Net deferred tax assets						3,423	3,240
Deferred tax assets, valuation allowance		$ 2,333				2,734	2,595	$ 2,333				$ 2,062
Foreign undistributed net earnings for which no deferred taxes have been provided						2,857
Noncurrent income taxes (Q)						$ 9	$ 193
Percentage of the effect of unrecognized tax benefit, if recorded						2.00%	1.00%	1.00%
Reductions for tax positions of prior years						$ 1	$ 0	$ 0
Interest and penalties recognized						0	1	1
Interest income on income tax related payments						1	1	$ 1
Amount accrued for payment of interest and penalties						$ 3	4
Minimum tax on book income of corporation	15.00%
Excise tax on net stock repurchases	1.00%
Excise tax for common stock repurchases	1.00%
Reversal of valuation allowance							58
Remaining cumulative income position period						3 years
Other Receivables [Member]
Income Taxes [Line Items]
Income tax benefits due to inflation reduction act tax credits						$ 36	36
Other Noncurrent Assets [Member]
Income Taxes [Line Items]
Income tax benefits due to inflation reduction act tax credits						71
Cost of Goods Sold [Member]
Income Taxes [Line Items]
Income tax benefits recorded in Cost of goods sold						$ 71	$ 36
Norway [Member] | Internal Reorganization [Member]
Income Taxes [Line Items]
Deferred income taxes (Q)		$ 30
AWAB [Member] | Alumar Refinery [Member]
Income Taxes [Line Items]
Corporate income tax rate						15.25%	34.00%	34.00%
Increase (decrease) in discrete income tax charge and benefit due tax holiday								$ (33)
Income tax holiday, description						The holiday related to production at the Alumar refinery was originally expected to end on December 31, 2027. During 2023, it was extended to December 31, 2032. The holiday related to the operation of the Juruti (Brazil) bauxite mine will end on December 31, 2026.
ASRI [Member] | Netherlands [Member]
Income Taxes [Line Items]
Tax expense (benefit)			$ (94)
ASRI [Member] | Norway [Member]
Income Taxes [Line Items]
Number of legal entities | LegalEntity		4
Number of legal entities reduced | LegalEntity		1
Foreign [Member]
Income Taxes [Line Items]
Deferred income taxes						$ 284
Percentage of net deferred tax asset relates to seven of Alcoa Corporation's income tax filers						100.00%
Number of Alcoa Corporation's income tax filers | Filer						5
Deferred tax liability						$ 337
Net deferred tax assets						2,333
Deferred tax assets, valuation allowance						$ 1,712
Income Tax Examination Year Under Examination						2014 2015 2016 2017 2018 2019 2020 2021 2022
Foreign [Member] | Australian Taxation Office [Member]
Income Taxes [Line Items]
Assessed income tax amount exclusive of interest and penalties paid				$ 74	$ 107
Noncurrent income taxes (Q)						$ 206	$ 199		$ 332		$ 293
Foreign [Member] | AofA [Member]
Income Taxes [Line Items]
Deferred income taxes						9
Foreign [Member] | AWAB [Member]
Income Taxes [Line Items]
Deferred tax assets, valuation allowance		$ 106				116	$ 154	106
Foreign [Member] | Alcoa Canada Company [Member]
Income Taxes [Line Items]
Deferred income taxes						113
Foreign [Member] | Alcoa Lauralco Management Company [Member]
Income Taxes [Line Items]
Deferred income taxes						83
Foreign [Member] | Alcoa Wolinbec Company [Member]
Income Taxes [Line Items]
Deferred income taxes						33
Foreign [Member] | Alcoa Islandi [Member]
Income Taxes [Line Items]
Deferred income taxes						19
Foreign [Member] | Espanola [Member]
Income Taxes [Line Items]
Deferred tax assets, valuation allowance		$ 217						$ 217				$ 150
Foreign [Member] | Fjaroaal [Member]
Income Taxes [Line Items]
Deferred income taxes						27
United States [Member]
Income Taxes [Line Items]
Deferred income taxes						0
Deferred tax liability						68
Net deferred tax assets						1,090
Deferred tax assets, valuation allowance						$ 1,022
Income Tax Examination Year Under Examination						2014 2015 2016 2017 2018