Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended				6 Months Ended
	Jul. 04, 2020	Dec. 31, 2019	Sep. 28, 2019	Jun. 29, 2019	Jul. 04, 2020	Jun. 29, 2019
Finite And Indefinite Lived Intangible Assets [Line Items]
Impairment of goodwill		$ 0
Goodwill	$ 2,190,144,000	2,201,063,000			$ 2,190,144,000
Finite-lived intangible assets	698,437,000	$ 742,186,000			698,437,000
Intangible asset amortization expense	20,700,000			$ 21,200,000	42,200,000	$ 42,700,000
Future amortization expense, in 2020	83,500,000				83,500,000
Future amortization expense, in 2021	82,300,000				82,300,000
Future amortization expense, in 2022	80,700,000				80,700,000
Future amortization expense, in 2023	80,000,000.0				80,000,000.0
Future amortization expense, in 2024	79,200,000				$ 79,200,000
Minimum [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, useful life					5 years
Maximum [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, useful life					22 years
Rebar Fabrication [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value		56.00%
Goodwill	347,800,000	$ 356,600,000			$ 347,800,000
Finite-lived intangible assets	61,300,000	67,200,000			61,300,000
Grating unit [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value			17.00%
Goodwill	$ 36,500,000	$ 36,800,000			$ 36,500,000