Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible asset amortization expense	$ 83,400,000	$ 85,700,000	$ 88,800,000
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
Impairment of goodwill	0	0	0
Goodwill	2,229,672,000	2,201,063,000	$ 2,184,336,000
Finite-lived intangible assets	$ 668,021,000	$ 742,186,000
Rebar Fabrication [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value	99.00%
Goodwill	$ 364,300,000
Finite-lived intangible assets	$ 58,800,000
Grating unit [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value	88.00%
Goodwill	$ 37,000,000.0
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