Income Taxes - Additional Information (Detail) € in Millions, $ 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, 2022 USD ($) Filer	Dec. 31, 2022 AUD ($) Filer	Dec. 31, 2021 USD ($)	Dec. 31, 2021 AUD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)	Dec. 31, 2020 AUD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2022 AUD ($)	Dec. 31, 2021 AUD ($)
Income Taxes [Line Items]
Corporate income tax rate						21.00%	21.00%	21.00%	21.00%	21.00%	21.00%	21.00%
Tax expense (benefit)						$ 664		$ 629		$ 187
Deferred income taxes (Q)						219		147		$ (26)
Deferred income taxes		$ 87				87
Deferred tax liability		538				538
Deferred tax assets		2,958				2,958		2,964
Foreign undistributed net earnings for which no deferred taxes have been provided		2,794				2,794
Noncurrent income taxes (Q)		215				$ 215		$ 191
Percentage of the effect of unrecognized tax benefit, if recorded						1.00%	1.00%	0.00%	0.00%	3.00%	3.00%	3.00%
Reductions for tax positions of prior years						$ 0		$ 0		$ 26
Interest and penalties recognized						1		0		0
Income related to accrued interest and penalties						1		0		13
Amount accrued for payment of interest and penalties		3				$ 3		$ 2
Minimum tax on book income of corporation	15.00%
Excise tax on net stock repurchases	1.00%
Secretariat of the Federal Revenue Bureau of Brazil [Member]
Income Taxes [Line Items]
Tax credit carryforward, limitations on use						30.00%	30.00%
Tax Authority, Spain [Member]
Income Taxes [Line Items]
Charge recorded in provision for income taxes to establish liability for estimated loss													$ 30	€ 26
Interest recorded in provision for income taxes to establish liability for estimated loss													$ 10	€ 9
Gain recorded from reversal of 2018 entry										32	€ 26
Reductions for tax positions of prior years										21	€ 17
Percentage of share of the estimated loss													49.00%	49.00%
Norway [Member] | Internal Reorganization [Member]
Income Taxes [Line Items]
Deferred income taxes (Q)		$ 30
Alcoa World Alumina Brasil [Member] | Alumar Refinery [Member]
Income Taxes [Line Items]
Corporate income tax rate						15.25%	15.25%	34.00%	34.00%
Increase (decrease) in discrete income tax charge and benefit due tax holiday						$ (33)				15
Income tax holiday, description						The holiday related to production at the Alumar refinery will end on December 31, 2027, and the holiday related to the operation of the Juruti (Brazil) bauxite mine will end on December 31, 2026.	The holiday related to production at the Alumar refinery will end on December 31, 2027, and 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
Valuation Allowance Against Increased Deferred Tax Asset [Member] | GILTI [Member]
Income Taxes [Line Items]
Income tax charge (benefit) due to implementing provisions of TCJA										138
U.S. Federal Net Operating Loss Carryforwards [Member] | GILTI [Member]
Income Taxes [Line Items]
Income tax charge (benefit) due to implementing provisions of TCJA										(138)
Foreign [Member]
Income Taxes [Line Items]
Deferred income taxes		$ 87				$ 87
Percentage of net deferred tax asset relates to seven of Alcoa Corporation's income tax filers						85.00%	85.00%
Number of Alcoa Corporation's income tax filers | Filer						5	5
Deferred tax liability		471				$ 471
Deferred tax assets		1,994				$ 1,994
Foreign [Member] | Latest Tax Year [Member]
Income Taxes [Line Items]
Income Tax Examination Year Under Examination						2021	2021
Foreign [Member] | Earliest Tax Year [Member]
Income Taxes [Line Items]
Income Tax Examination Year Under Examination						2012	2012
Foreign [Member] | Australian Taxation Office [Member]
Income Taxes [Line Items]
Assessed income tax amount exclusive of interest and penalties paid				$ 74	$ 107
Lower cash tax payments						$ 15	$ 22	$ 14	$ 19	169		$ 219
Noncurrent income taxes (Q)		174				174		174							$ 260	$ 238
Foreign [Member] | AofA [Member]
Income Taxes [Line Items]
Deferred tax liability		207				207
Foreign [Member] | AofA [Member] | Australian Taxation Office [Member]
Income Taxes [Line Items]
Lower cash tax payments						15	$ 22	14	$ 19	$ 169		$ 219
Foreign [Member] | Alcoa World Alumina Brasil [Member]
Income Taxes [Line Items]
Deferred income taxes		96				96
Foreign [Member] | Alcoa Canada Company [Member]
Income Taxes [Line Items]
Deferred income taxes		108				108
Foreign [Member] | Alcoa Lauralco Management Company [Member]
Income Taxes [Line Items]
Deferred income taxes		43				43
Foreign [Member] | Alcoa Wolinbec Company [Member]
Income Taxes [Line Items]
Deferred income taxes		33				33
Foreign [Member] | Espanola [Member]
Income Taxes [Line Items]
Deferred tax assets		217				217		150
Foreign [Member] | Espanola [Member]
Income Taxes [Line Items]
Deferred tax assets								$ 103
United States [Member]
Income Taxes [Line Items]
Deferred tax liability		67				67
Deferred tax assets		$ 964				$ 964
United States [Member] | Latest Tax Year [Member]
Income Taxes [Line Items]
Income Tax Examination Year Under Examination						2018	2018