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Payment amount refund percentage.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Includes expenses related to certain asset retirement obligations.

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Carrying amount as of the balance sheet date of unearned revenue or income, not otherwise specified in the taxonomy, which is expected to be taken into income after one year or beyond the normal operating cycle, if longer and noncurrent obligations not separately disclosed in the balance sheet (other liabilities, noncurrent).

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A credit or adjustment for government or taxing authority authorized decrease in taxes owed as a result of meeting certain tax policy conditions.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Contingencies - Additional Information - 1 (Detail) R$ in Millions, $ in Millions			1 Months Ended											3 Months Ended	9 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$)	Sep. 30, 2020 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2023 BRL (R$)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 AUD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 AUD ($)	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															$ 538,000,000				$ 486,000,000
AWAC [Member] \| Alumina Limited [Member]
Loss Contingencies [Line Items]
Non-controlling interest, ownership percentage															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																								$ 137,000,000	$ 214
Notices include claims for compounded interest on the tax amount																								$ 452,000,000	$ 707
Proposed administrative penalties	$ 82,000,000	$ 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%
Other noncurrent liabilities and deferred credits															$ 182,000,000			$ 284	$ 174,000,000	$ 260
Tax assessment deposit															$ 68,000,000			$ 107
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	R$ 19				R$ 220
Percentage of penalty of the gross disallowed amount											50.00%
Value added tax receivable			$ 6,000,000	R$ 31	$ 16,000,000	R$ 84	$ 9,000,000	R$ 44	$ 14,000,000	R$ 65		$ 41,000,000	R$ 82
Alcoa Corporation [Member] \| AWAC [Member]
Loss Contingencies [Line Items]
Ownership interest percentage															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															$ 47,000,000	R$ 239
Aviles And La Coruna Facilities [Member]
Loss Contingencies [Line Items]
Restructuring and other charges, net																	$ 79,000,000