Segments - Schedule of Net Sale by Product to External Customers (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 05, 2025	Jun. 29, 2024	Jul. 05, 2025	Jun. 29, 2024
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	$ 8,456	$ 8,077	$ 16,286	$ 16,214
Sheet [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	2,476	2,396	4,685	5,106
Bar [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	1,397	1,361	2,889	2,696
Structural [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	694	559	1,338	1,170
Plate [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	686	542	1,248	1,054
Tubular Products [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	380	345	744	713
Rebar Fabrication [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	487	462	895	875
Joist & Deck [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	564	598	1,062	1,197
Building Systems [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	337	361	615	675
Other Steel Products [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	889	937	1,746	1,760
Raw Materials [Member]
Segment Reporting Information [Line Items]
Revenue From Contract With Customer Excluding Assessed Tax	$ 546	$ 516	$ 1,064	$ 968