Divestitures - Additional Information (Detail) - Warrick Rolling Mill [Member] - Disposal Group, Held-for-Sale, Not Discontinued Operations [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Business Disposition [Line Items]
Estimated Liabilities For Future Site Separation Commitment Charge			$ 17	$ 5
Payments against the reserve	$ 19	$ 13	44	$ 22
Remaining reserve	$ 19		$ 19