Contingencies and Commitments - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) Project	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Loss Contingencies [Line Items]
Liabilities incurred	$ 39	$ 32	$ 21
Payments against the reserve	55	26	23
Reversals of previously recorded liabilities	1	30	17
Environmental remediation reserve balance, current	$ 66	$ 58
Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities	Other current liabilities
Active or future remediation for significant sites	$ 211	$ 234
Accrued environmental reserves	268	284	309	$ 322
Former East St. Louis Site [Member]
Loss Contingencies [Line Items]
Liabilities incurred		4
Magnesium Smelter Facility in Addy [Member]
Loss Contingencies [Line Items]
Liabilities incurred		14
Point Henry Site [Member]
Loss Contingencies [Line Items]
Liabilities incurred		6
Environmental activiteis
Loss Contingencies [Line Items]
Liabilities incurred		9
Intalco Aluminum Smelter [Member]
Loss Contingencies [Line Items]
Liabilities incurred	$ 14
Massena East Site [Member]
Loss Contingencies [Line Items]
Reversals of previously recorded liabilities		18
Suralco [Member]
Loss Contingencies [Line Items]
Reversals of previously recorded liabilities		5
Closed Site in Brazil [Member]
Loss Contingencies [Line Items]
Reversals of previously recorded liabilities		6	5
Closed Suriname Site [Member]
Loss Contingencies [Line Items]
Reversals of previously recorded liabilities			7
Closed Tennessee Site [Member]
Loss Contingencies [Line Items]
Reversals of previously recorded liabilities			$ 5
Massena, New York [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Environmental remediation work completion period	4 years
Massena, New York [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Environmental remediation work completion period	8 years
Longview, Washington [Member] | Ongoing Remediation Work [Member]
Loss Contingencies [Line Items]
Liabilities incurred	$ 13
Addy, Washington [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Environmental remediation work completion period	3 years
Addy, Washington [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Environmental remediation work completion period	5 years
Ferndale Washington [Member]
Loss Contingencies [Line Items]
Post-closure maintenance and monitoring period	5 years
Other Sites [Member]
Loss Contingencies [Line Items]
Liabilities incurred	$ 12
Number of remediation projects | Project	32
Accrued environmental reserves	$ 57	$ 50