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Contingencies and Commitments - Additional Information - 1 (Detail) $ in Millions			1 Months Ended											3 Months Ended	6 Months Ended	12 Months Ended
	Sep. 17, 2020 USD ($)	Sep. 17, 2020 AUD ($)	Aug. 31, 2022 USD ($)	Aug. 31, 2022 BRL (R$)	Jul. 31, 2022 USD ($)	Jul. 31, 2022 BRL (R$)	Mar. 31, 2022 USD ($)	Mar. 31, 2022 BRL (R$)	Feb. 28, 2022 USD ($)	Feb. 28, 2022 BRL (R$)	Mar. 31, 2013 USD ($)	May 31, 2012 USD ($)	May 31, 2012 BRL (R$)	Sep. 30, 2020 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2023 BRL (R$)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2023 AUD ($)	Dec. 31, 2022 AUD ($)	Jul. 31, 2022 BRL (R$)	Feb. 28, 2022 BRL (R$)	Sep. 30, 2020 AUD ($)	Jul. 07, 2020 USD ($)	Jul. 07, 2020 AUD ($)	Mar. 31, 2013 BRL (R$)
Loss Contingencies [Line Items]
Other noncurrent liabilities and deferred credits (U)															$ 568,000,000	$ 568,000,000		$ 486,000,000
Restructuring and other charges, net (D)																$ 184,000,000		696,000,000	$ 1,128,000,000
Payment for settlements to former employees															$ 76,000,000
AWAC [Member] \| Alumina Limited [Member]
Loss Contingencies [Line Items]
Non-controlling interest, ownership percentage															40.00%	40.00%				40.00%
Australian Taxation Office [Member] \| Foreign Jurisdiction [Member] \| AofA [Member]
Loss Contingencies [Line Items]
Additional income tax payable, exclusive of interest and penalties																									$ 145,000,000	$ 214
Notices include claims for compounded interest on the tax amount																									$ 481,000,000	$ 707
Proposed administrative penalties	$ 87,000,000	$ 128
Payment of dispute resolution practices income tax percentage														50.00%
Assessed income tax amount exclusive of interest and penalties														$ 74,000,000										$ 107
Payment amount refund percentage														50.00%
Tax assessment deposit															$ 73,000,000	$ 73,000,000				$ 107
Other noncurrent liabilities and deferred credits (U)															$ 199,000,000	$ 199,000,000		174,000,000		$ 293	$ 260
Alcoa World Alumina Brasil [Member] \| Brazilian Federal Revenue Office [Member]
Loss Contingencies [Line Items]
Disallowed tax credits					$ 13,000,000				$ 4,000,000		$ 110,000,000											R$ 70,000,000	R$ 19,000,000				R$ 220,000,000
Percentage of penalty of the gross disallowed amount											50.00%
Value added tax receivable			$ 6,000,000	R$ 31,000,000	$ 16,000,000	R$ 84,000,000	$ 9,000,000	R$ 44,000,000	$ 14,000,000	R$ 65,000,000		$ 41,000,000	R$ 82,000,000
Alcoa Corporation [Member] \| AWAC [Member]
Loss Contingencies [Line Items]
Ownership interest percentage															60.00%	60.00%				60.00%
Minimum [Member] \| Alcoa World Alumina Brasil [Member] \| Brazilian Federal Revenue Office [Member]
Loss Contingencies [Line Items]
Charge recorded in provision for income taxes to establish liability for estimated loss																$ 0
Maximum [Member] \| Alcoa World Alumina Brasil [Member] \| Brazilian Federal Revenue Office [Member]
Loss Contingencies [Line Items]
Charge recorded in provision for income taxes to establish liability for estimated loss																$ 49,000,000	R$ 239,000,000
Aviles and La Coruna Smelters [Member] \| Maximum [Member] \| Parter Capital Group A G \| Spain [Member] \| Aviles and La Coruea Aluminum Facilities [Member]
Loss Contingencies [Line Items]
Financial Contributions																			95,000,000
Financial contributions paid to buyer in relation to divestiture																			$ 78,000,000
Aviles and La Coruna Facilities [Member]
Loss Contingencies [Line Items]
Restructuring and other charges, net (D)																		$ 79,000,000