Goodwill and Other Intangible Assets - Summary of Goodwill which is Included in Other Noncurret Assets (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill	$ 144	$ 145
Other Noncurrent Assets [Member]
Goodwill [Line Items]
Goodwill	144	145
Corporate Segment [Member]
Goodwill [Line Items]
Accumulated impairment losses	742	742
Corporate Segment [Member] | Other Noncurrent Assets [Member]
Goodwill [Line Items]
Goodwill	140	141
Bauxite [Member]
Goodwill [Line Items]
Segment reporting, goodwill	46
Bauxite [Member] | Other Noncurrent Assets [Member]
Goodwill [Line Items]
Goodwill	2	2
Alumina [Member]
Goodwill [Line Items]
Segment reporting, goodwill	94
Alumina [Member] | Other Noncurrent Assets [Member]
Goodwill [Line Items]
Goodwill	$ 2	$ 2