Restructuring and Other Charges, Net - Additional Information (Detail) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Employees	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)		$ 22	$ 652	$ 195	$ 702
Australia [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with employee termination and severance costs | Employees				90
Restructuring and other charges, net (D)				$ 6
Pension Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Settlement of certain other postretirement benefits	[1]		626	21	626
Restructuring and other charges, net (D)			626		626
MRN [Member]
Restructuring Cost and Reserve [Line Items]
Asset impairments					58
Alcoa Corporation [Member]
Restructuring Cost and Reserve [Line Items]
Noncurrent portion of the reserve		21		21		$ 3
Magnesium Smelter Facility in Addy [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)			29		29
Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Asset impairments				50
Severance costs				$ 1
Number of employees associated with employee termination and severance costs | Employees				12
Cash outlays expected in 2024				$ 85
Cash outlays expected in 2025				85
Cash outlays spent in 2023		1		1
Restructuring and other charges, net (D)				101
Cost of Goods Sold [Member] | Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Other costs				16
Restructuring and Other Charges [Member] | San Ciprian Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)				47
2023 Restructuring Plans Action [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)		22		195
Environmental and Asset Retirement Obligation Reserves [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring And Other Charges		15		15
Legal Disputes Related to 2019 Divestiture [Member] | Aviles and La Coruna Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)					79
Additional Contract Costs [Member] | Wenatchee (Washington) and Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)					(6)
Closure Cost [Member] | Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Asset impairments				101
Restructuring and other charges, net (D)				117
Valuation Allowance on Brazil Value-Added Taxes [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)					83
Remediation at Previously Closed Sites [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)			$ (3)		$ (1)
Certain Employee Obligations [Member] | San Ciprian Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)				47
Environmental and Demolition Obligation [Member] | Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)				50
Severance and Employee Termination Costs [Member] | Australia [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)		$ 7		10
Other Miscellaneous Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)				$ 1

[1] These amounts were reported in Restructuring and other charges, net on the accompanying Statements of Consolidated Operations (see Note D) and Cash Flows.