Summary of Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) Reporting_Unit Segment $ / shares	Dec. 31, 2021 USD ($) $ / shares	Dec. 31, 2020 $ / shares	Sep. 30, 2022	Jan. 31, 2021	Mar. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Original maturity of cash equivalents	3 months
Segment Allocation, Goodwill Recognized | $	$ 145	$ 144
Number of operating segments | Segment	3
Fair value of stock options granted | $ / shares	$ 0	$ 0	$ 6.12
Maximum hedging contracts period, in years	5 years
Accounting Standards Update 2020-04 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, immaterial effect					true	true
Accounting Standards Update 2022-04 [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, immaterial effect				true
Change in accounting principle, accounting standards update, early adoption				true
Alcoa Corporation [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of reporting units for goodwill allocation	4
Alcoa Corporation [Member] | Bauxite [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of reporting units for goodwill allocation	1
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	11 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