Restructuring and Other Charges, Net - Additional Information (Detail) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) Employees	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)		$ 24	$ (75)	$ 173	$ 50
Pension Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Settlement of certain other postretirement benefits	[1]	21		21
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		30		30		$ 3
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 over next three years				$ 85
Cash outlays spent in 2023				25
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)		24		173
Legal Disputes Related to 2019 Divestiture [Member] | Aviles and La Coruna (Spain) Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)			2		79
Additional Contract Costs [Member] | Wenatchee (Washington) and Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)			3		(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)		(83)
Remediation at Previously Closed Sites [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)			$ 3		$ 2
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]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)		2		2
Other Miscellaneous Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)		$ 1		$ 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.