Restructuring and Other Charges, Net (2023 Actions) - Additional Information (Detail) kt in Thousands, $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2021 Employees kt	Dec. 31, 2023 USD ($) Employees	Dec. 31, 2022 USD ($) Employees	Dec. 31, 2021 USD ($) Employees
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		$ 184	$ 696	$ 1,128
Severance costs		11	1	1
Restart costs		35
Settlement and curtailment of certain other postretirement benefits		(21)	(632)	(977)
Asset impairments		$ 50	$ 58	$ 75
Number of employees under defined benefit plan | Employees	14,000	530	4,400	14,000
Australia [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		$ 6
Number of employees associated with employee termination and severance costs | Employees		90
Cash outlays		$ 1
Intalco Aluminum Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		101
Group Annuity Contract [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		21	$ 635	$ 858
Group Annuity Contract [Member] | Restructuring And Other Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net				63
Pension Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		$ 235	1,000	1,500
Number of employees under defined benefit plan | Employees		17,000
Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		$ 101
Number of employees associated with employee termination and severance costs | Employees		12
Severance costs		$ 1
Asset impairments		50
Intalco [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Other costs		16
San Ciprian Facility [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		53
Commitments for capital improvement costs		78
Capital improvement costs		118
Cash outlays		7
Restricted cash		91
Restart costs		35
Curtailment of smelting capacity | kt	228
San Ciprian Facility [Member] | Restructuring And Other Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		53
Warrick Rolling Mill [Member] | Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Charges for write-off remaining net book value of assets		1
Warrick Rolling Mill [Member] | Restructuring And Other Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		1
2023 Restructuring Plans Action [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		184
Severance and Exit Costs [Member] | Warrick Rolling Mill [Member]
Restructuring Cost and Reserve [Line Items]
Settlement and curtailment of certain other postretirement benefits				9
Additional Contract Costs [Member] | Wenatchee (Washington) and Intalco (Washington) [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		1	7	13
Severance and Employee Termination Costs [Member] | Australia [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		11
Additional Environmental and Asset Retirement [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		17	26	$ 11
Closure Cost [Member] | Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		117
Cash outlays		31
Environmental and Demolition Obligation [Member] | Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		50
Cash outlays		54
Environmental and Demolition Obligation [Member] | Reserved for prior periods [Member] | Intalco [Member]
Restructuring Cost and Reserve [Line Items]
Cash outlays		4
Remediation at Previously Closed Sites [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		2	$ 34
Additional Asset Retirement [Member] | Warrick Rolling Mill [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		1
Unused Carbon Credits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		$ 19