Properties, Plants, and Equipment, Net - Schedule of Properties, Plants, and Equipment, Net (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Less: accumulated depreciation, depletion, and amortization	$ 13,596	$ 13,112
Properties, plants, and equipment excluding construction work-in-progress	6,216	5,973
Construction work-in-progress	569	520
Properties, plants, and equipment, net	6,785	6,493
Land [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	257	253
Structures [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	8,096	7,480
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	11,459	11,352
Property Plant And Equipment Other Than Construction In Progress [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	19,812	19,085
Operating Segments [Member] | Bauxite Mining and Alumina Refining [Member] | Structures [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	4,085	3,515
Operating Segments [Member] | Bauxite Mining and Alumina Refining [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	4,352	4,227
Operating Segments [Member] | Aluminum Smelting and Casting [Member] | Structures [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	3,274	3,265
Operating Segments [Member] | Aluminum Smelting and Casting [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	5,781	5,813
Operating Segments [Member] | Energy [Member] | Structures [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	380	354
Operating Segments [Member] | Energy [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	869	851
Other [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, net	392	364
Other [Member] | Structures [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	457	461
Other [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross	$ 357	$ 346