Contingencies - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) Project	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Loss Contingencies [Line Items]
Liabilities incurred		$ 4	$ 1	$ 18	$ 39
Payments against the reserve	$ 10	16	16	23	55
Reversals of previously recorded liabilities				(1)	1
Environmental remediation reserve balance, current	$ 61		$ 61		$ 66
Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Current		Other Liabilities, Current		Other Liabilities, Current
Active or future remediation for significant sites	$ 199		$ 199		$ 211
Accrued environmental reserves	252		$ 252		268	$ 284
Ongoing Remediation Work [Member]
Loss Contingencies [Line Items]
Liabilities incurred		$ 4
Intalco Aluminum Smelter [Member]
Loss Contingencies [Line Items]
Liabilities incurred				$ 14
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
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]
Number of remediation projects | Project			32
Accrued environmental reserves	$ 53		$ 53		$ 57