Other Financial Information - Schedule of Other Noncurrent Liabilities and Deferred Credits (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Other Financial Information [Abstract]
Operating lease obligations	$ 223	$ 104
Noncurrent accrued tax liability	206	199
Accrued compensation and retirement costs	95	94
Deferred energy credits	36	42
Value added tax credits payable to Arconic Corporation	26	58
Deferred alumina sales revenue	12	20
Noncurrent restructuring reserve	8	15
Other	50	36
Other noncurrent liabilities and deferred credits, total	$ 656	$ 568