Segment - Schedule of Net Sale by Product to External Customers (Detail) - USD ($) $ in Millions	3 Months Ended
	Apr. 05, 2025	Mar. 30, 2024
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	$ 7,830	$ 8,137
Sheet [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	2,209	2,710
Bar [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	1,492	1,335
Structural [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	644	611
Plate [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	562	513
Tubular Products [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	364	369
Rebar Fabrication [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	408	412
Joist & Deck [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	498	599
Building Systems [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	278	314
Other Steel Products [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	857	823
Raw Materials [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	$ 518	$ 451