Intangibles - Intangible Assets Other Than Goodwill and Trade Names (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of accumulated amortization	$ 602,619	$ 601,013
Patents And Other
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of accumulated amortization	17,651	17,554
Intangible assets, accumulated amortization	43,122	43,021
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of accumulated amortization	584,968	583,459
Intangible assets, accumulated amortization	$ 137,308	$ 126,824