Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Dec. 31, 2018
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible asset amortization expense	$ 21,500	$ 22,500
Future amortization expense, in 2019	87,100
Future amortization expense, in 2020	84,700
Future amortization expense, in 2021	83,500
Future amortization expense, in 2022	81,200
Future amortization expense, in 2023	80,000
Impairment of goodwill	0
Goodwill	2,183,677		$ 2,184,336
Finite-lived intangible assets	$ 806,888		828,504
Grating unit [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value	19.00%
Goodwill	$ 36,600
Finite-lived intangible assets	$ 3,600
Rebar Fabrication [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value	8.00%
Goodwill	$ 352,500		353,000
Finite-lived intangible assets	$ 74,000		$ 76,700
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