Contingencies and Commitments - Additional Information - 2 (Detail) $ in Millions		1 Months Ended	12 Months Ended
	Apr. 08, 2015 USD ($) Refinery Installment	Apr. 30, 2016 USD ($) Refinery	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2022 AUD ($)	Dec. 31, 2021 AUD ($)	Aug. 31, 2017 USD ($)	Jun. 30, 2015 USD ($)
Loss Contingencies [Line Items]
Number of alumina refineries to be powered under supplied agreement | Refinery		3
Total asset			$ 311,000,000	$ 377,000,000
Guarantees of third party related to project financing			$ 0	0
Line of credit renew or expire starting year			2023
Line of credit renew or expire ending year			2024
Letters of credit, total amount committed			$ 293,000,000
Outstanding bank guarantees and letters of credit			$ 14,000,000
Letter of credit agreement, expiration date			Jun. 27, 2024
Total amount committed under outstanding surety bonds			$ 174,000,000
Minimum [Member]
Loss Contingencies [Line Items]
Surety bonds, expiration date			2023
Maximum [Member]
Loss Contingencies [Line Items]
Surety bonds, expiration date			2027
Alcoa Corporation [Member]
Loss Contingencies [Line Items]
Total amount committed under outstanding surety bonds			$ 11,000,000
Parent Co [Member]
Loss Contingencies [Line Items]
Total amount committed under outstanding surety bonds			3,000,000
Parent Co [Member]
Loss Contingencies [Line Items]
Outstanding bank guarantees and letters of credit			8,000,000
Standby Letter of Credit Agreement [Member]
Loss Contingencies [Line Items]
Line of credit facility, outstanding borrowings			131,000,000
Principal amount of debt								$ 200,000,000
Letter of Credit [Member]
Loss Contingencies [Line Items]
Line of credit facility, outstanding borrowings			131,000,000
AofA [Member] | Service Agreements [Member] | Alcoa Corporation [Member]
Loss Contingencies [Line Items]
Number of alumina refineries to be powered under supplied agreement | Refinery	3
Number of installments | Installment	2
Gas supply agreement prepayment amount	$ 500,000,000
Total asset			348,000,000	417,000,000		$ 519	$ 571
AofA [Member] | Service Agreements [Member] | Prepaid Expenses and Other Current Assets [Member] | Alcoa Corporation [Member]
Loss Contingencies [Line Items]
Total asset			37,000,000	40,000,000
AofA [Member] | Service Agreements [Member] | Other Noncurrent Assets [Member] | Alcoa Corporation [Member]
Loss Contingencies [Line Items]
Total asset			$ 311,000,000	377,000,000
AofA [Member] | Service Agreements [Member] | First Installment [Member] | Alcoa Corporation [Member]
Loss Contingencies [Line Items]
Gas supply agreement prepayment amount									$ 300,000,000
AofA [Member] | Service Agreements [Member] | Second Installment [Member] | Alcoa Corporation [Member]
Loss Contingencies [Line Items]
Gas supply agreement prepayment amount		$ 200,000,000
Energy Obligation [Member]
Loss Contingencies [Line Items]
Expiration date of unconditional purchase obligations for energy starting year			2040
Expiration date of unconditional purchase obligations for energy ending year			2041
Purchase obligations due in 2023			$ 59,000,000
Purchase obligations due in 2024			62,000,000
Purchase obligations due in 2025			64,000,000
Purchase obligations due in 2026			66,000,000
Purchase obligations due in 2027			68,000,000
Purchase obligations due thereafter			716,000,000
Purchase obligations expenditures			58,000,000	$ 86,000,000	$ 79,000,000
Energy Raw Materials And Other Goods And Services [Member]
Loss Contingencies [Line Items]
Purchase obligations due in 2023			4,402,000,000
Purchase obligations due in 2024			2,328,000,000
Purchase obligations due in 2025			2,004,000,000
Purchase obligations due in 2026			1,665,000,000
Purchase obligations due in 2027			1,518,000,000
Purchase obligations due thereafter			$ 10,392,000,000