Restructuring and Other Charges, Net (2020 Actions) - Additional Information (Detail) $ in Millions		12 Months Ended
	Apr. 30, 2020 kt	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) Employee
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)		$ 696	$ 1,128	$ 104
Settlement and curtailment of certain other postretirement benefits		$ (632)	$ (977)	(58)
Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)				$ 28
Curtailment of smelting capacity | kt	230
Curtailed smelting capacity | kt	49
Number of affected employees associated with employee termination and severance costs | Employee				685
Contract termination costs				$ 16
Net curtailment gain				1
2020 Restructuring Plans Action [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)				104
Settlement and curtailment of certain other postretirement benefits				59
Severance and Exit Costs [Member] | 2020 Restructuring Plans Action [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges (reversal)				28
Additional Contract Costs [Member] | 2020 Restructuring Plans Action [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)				20
Severance and Employee Termination Costs [Member] | Intalco [Member] | Alcoa Corporation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net (D)				$ 13