Revenue - Schedule of Net Sales Disaggregates by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Oct. 01, 2022	Sep. 30, 2023	Oct. 01, 2022
Revenue from Contract with Customers [Line Items]
Revenues	$ 8,775,734	$ 10,500,755	$ 27,008,970	$ 32,788,511
Sheet [Member]
Revenue from Contract with Customers [Line Items]
Revenues	2,351,705	2,712,426	7,100,216	9,511,822
Bar [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,448,433	1,761,335	4,646,285	5,581,529
Structural [Member]
Revenue from Contract with Customers [Line Items]
Revenues	626,633	785,930	1,846,892	2,352,322
Plate [Member]
Revenue from Contract with Customers [Line Items]
Revenues	664,708	648,462	2,043,115	2,237,156
Tubular Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	370,472	459,427	1,246,006	1,583,818
Rebar Fabrication [Member]
Revenue from Contract with Customers [Line Items]
Revenues	604,684	628,923	1,718,615	1,653,155
Joist [Member]
Revenue from Contract with Customers [Line Items]
Revenues	528,018	789,249	1,802,809	2,089,366
Deck [Member]
Revenue from Contract with Customers [Line Items]
Revenues	411,352	634,901	1,370,570	1,768,224
Other Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,321,443	1,574,607	3,816,828	4,158,580
Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	448,286	505,495	1,417,634	1,852,539
Steel Mills [Member]
Revenue from Contract with Customers [Line Items]
Revenues	5,091,479	5,908,153	15,636,508	19,682,829
Steel Mills [Member] | Sheet [Member]
Revenue from Contract with Customers [Line Items]
Revenues	2,351,705	2,712,426	7,100,216	9,511,822
Steel Mills [Member] | Bar [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,448,433	1,761,335	4,646,285	5,581,529
Steel Mills [Member] | Structural [Member]
Revenue from Contract with Customers [Line Items]
Revenues	626,633	785,930	1,846,892	2,352,322
Steel Mills [Member] | Plate [Member]
Revenue from Contract with Customers [Line Items]
Revenues	664,708	648,462	2,043,115	2,237,156
Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	3,235,969	4,087,107	9,954,828	11,253,143
Steel Products [Member] | Tubular Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	370,472	459,427	1,246,006	1,583,818
Steel Products [Member] | Rebar Fabrication [Member]
Revenue from Contract with Customers [Line Items]
Revenues	604,684	628,923	1,718,615	1,653,155
Steel Products [Member] | Joist [Member]
Revenue from Contract with Customers [Line Items]
Revenues	528,018	789,249	1,802,809	2,089,366
Steel Products [Member] | Deck [Member]
Revenue from Contract with Customers [Line Items]
Revenues	411,352	634,901	1,370,570	1,768,224
Steel Products [Member] | Other Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,321,443	1,574,607	3,816,828	4,158,580
Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	448,286	505,495	1,417,634	1,852,539
Raw Materials [Member] | Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	$ 448,286	$ 505,495	$ 1,417,634	$ 1,852,539