Revenue - Schedule of Net Sales Disaggregates by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2024	Apr. 01, 2023
Revenue from Contract with Customers [Line Items]
Revenues	$ 8,137,083	$ 8,709,980
Sheet [Member]
Revenue from Contract with Customers [Line Items]
Revenues	2,710,337	2,102,694
Bar [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,334,898	1,598,128
Structural [Member]
Revenue from Contract with Customers [Line Items]
Revenues	611,007	638,307
Plate [Member]
Revenue from Contract with Customers [Line Items]
Revenues	512,536	640,128
Tubular Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	368,724	438,983
Rebar Fabrication [Member]
Revenue from Contract with Customers [Line Items]
Revenues	412,341	498,117
Joist [Member]
Revenue from Contract with Customers [Line Items]
Revenues	330,601	635,816
Deck [Member]
Revenue from Contract with Customers [Line Items]
Revenues	268,630	485,443
Building Systems [Member]
Revenue from Contract with Customers [Line Items]
Revenues	314,013	281,910
Other Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	822,559	935,728
Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	451,437	454,726
Steel Mills [Member]
Revenue from Contract with Customers [Line Items]
Revenues	5,168,778	4,979,257
Steel Mills [Member] | Sheet [Member]
Revenue from Contract with Customers [Line Items]
Revenues	2,710,337	2,102,694
Steel Mills [Member] | Bar [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,334,898	1,598,128
Steel Mills [Member] | Structural [Member]
Revenue from Contract with Customers [Line Items]
Revenues	611,007	638,307
Steel Mills [Member] | Plate [Member]
Revenue from Contract with Customers [Line Items]
Revenues	512,536	640,128
Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	2,516,868	3,275,997
Steel Products [Member] | Tubular Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	368,724	438,983
Steel Products [Member] | Rebar Fabrication [Member]
Revenue from Contract with Customers [Line Items]
Revenues	412,341	498,117
Steel Products [Member] | Joist [Member]
Revenue from Contract with Customers [Line Items]
Revenues	330,601	635,816
Steel Products [Member] | Deck [Member]
Revenue from Contract with Customers [Line Items]
Revenues	268,630	485,443
Steel Products [Member] | Building Systems [Member]
Revenue from Contract with Customers [Line Items]
Revenues	314,013	281,910
Steel Products [Member] | Other Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	822,559	935,728
Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	451,437	454,726
Raw Materials [Member] | Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	$ 451,437	$ 454,726