Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2023 Reporting_Unit Segment
Summary Of Significant Accounting Policies [Line Items]
Original maturity of cash equivalents	3 months
Number of operating segments | Segment	2
Maximum hedging contracts period, in years	5 years
Alcoa Corporation [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of reporting units for goodwill allocation	3
Alcoa Corporation [Member] | Alumina [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of reporting units for goodwill allocation	1
Alcoa Corporation [Member] | Aluminum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of reporting units for goodwill allocation	2
Minimum [Member] | Bauxite Mining [Member]
Summary Of Significant Accounting Policies [Line Items]
Period of mining	1 year
Maximum [Member] | Pension and other postretirement benefit plan [Member]
Summary Of Significant Accounting Policies [Line Items]
Weighted average discount rate yield curve	10 years
Weighted average discount rate yield curve	5 years
Maximum [Member] | Bauxite Mining [Member]
Summary Of Significant Accounting Policies [Line Items]
Period of mining	5 years