Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible asset amortization expense		$ 85,700,000	$ 88,800,000	$ 91,200,000
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	79,100,000	79,100,000
Future amortization expense, in 2024	79,200,000	79,200,000
Impairment of goodwill		0	0	0
Goodwill	2,201,063,000	2,201,063,000	2,184,336,000	$ 2,196,058,000
Finite-lived intangible assets	742,186,000	$ 742,186,000	$ 828,504,000
Trade Names [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Non-cash impairment charge	8,600,000
Rebar Fabrication [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value		56.00%
Goodwill	356,600,000	$ 356,600,000
Finite-lived intangible assets	67,200,000	$ 67,200,000
Grating unit [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Percentage of fair value exceeded carrying value		17.00%
Goodwill	36,800,000	$ 36,800,000
Intangible assets written off	$ 3,300,000
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