Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended			12 Months Ended
	Apr. 03, 2021	Dec. 31, 2020	Apr. 04, 2020	Dec. 31, 2020
Finite And Indefinite Lived Intangible Assets [Line Items]
Impairment of goodwill		$ 0
Goodwill	$ 2,235,183,000	2,229,672,000		$ 2,229,672,000
Finite-lived intangible assets	647,479,000	668,021,000		$ 668,021,000
Intangible asset amortization expense	21,100,000		$ 21,500,000
Future amortization expense, in 2021	82,700,000
Future amortization expense, in 2022	81,100,000
Future amortization expense, in 2023	80,400,000
Future amortization expense, in 2024	79,600,000
Future amortization expense, in 2025	$ 78,600,000
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				99.00%
Goodwill	$ 368,200,000	364,300,000		$ 364,300,000
Finite-lived intangible assets	56,800,000	58,800,000		$ 58,800,000
Grating unit [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value				88.00%
Goodwill	$ 37,200,000	$ 37,000,000.0		$ 37,000,000.0