Revenue - Schedule of Net Sales Disaggregates by Major Source (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 02, 2022	Apr. 03, 2021
Revenue from Contract with Customers [Line Items]
Revenues	$ 10,493,282	$ 7,017,140
Sheet [Member]
Revenue from Contract with Customers [Line Items]
Revenues	3,183,063	2,351,455
Bar [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,827,731	1,261,042
Structural [Member]
Revenue from Contract with Customers [Line Items]
Revenues	783,271	477,195
Plate [Member]
Revenue from Contract with Customers [Line Items]
Revenues	724,544	519,085
Tubular Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	610,300	374,653
Rebar Fabrication [Member]
Revenue from Contract with Customers [Line Items]
Revenues	445,232	386,557
Joist [Member]
Revenue from Contract with Customers [Line Items]
Revenues	612,235	229,129
Deck [Member]
Revenue from Contract with Customers [Line Items]
Revenues	550,909	193,413
Other Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,104,412	626,303
Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	651,585	598,308
Steel Mills [Member]
Revenue from Contract with Customers [Line Items]
Revenues	6,518,609	4,608,777
Steel Mills [Member] | Sheet [Member]
Revenue from Contract with Customers [Line Items]
Revenues	3,183,063	2,351,455
Steel Mills [Member] | Bar [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,827,731	1,261,042
Steel Mills [Member] | Structural [Member]
Revenue from Contract with Customers [Line Items]
Revenues	783,271	477,195
Steel Mills [Member] | Plate [Member]
Revenue from Contract with Customers [Line Items]
Revenues	724,544	519,085
Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	3,323,088	1,810,055
Steel Products [Member] | Tubular Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	610,300	374,653
Steel Products [Member] | Rebar Fabrication [Member]
Revenue from Contract with Customers [Line Items]
Revenues	445,232	386,557
Steel Products [Member] | Joist [Member]
Revenue from Contract with Customers [Line Items]
Revenues	612,235	229,129
Steel Products [Member] | Deck [Member]
Revenue from Contract with Customers [Line Items]
Revenues	550,909	193,413
Steel Products [Member] | Other Steel Products [Member]
Revenue from Contract with Customers [Line Items]
Revenues	1,104,412	626,303
Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	651,585	598,308
Raw Materials [Member] | Raw Materials [Member]
Revenue from Contract with Customers [Line Items]
Revenues	$ 651,585	$ 598,308