Other (Income) Expenses, Net - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Other Non Operating Income Expense [Line Items]
Net (gain) loss from asset sales	$ (132)	$ (174)
Former Eastalco Site Sale And Warrick Rolling Mill [Member]
Other Non Operating Income Expense [Line Items]
Net (gain) loss from asset sales	$ (120)
Gum Springs [Member]
Other Non Operating Income Expense [Line Items]
Net (gain) loss from asset sales		$ (181)