Intangibles - Intangible Assets Other Than Goodwill and Trade Names (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of accumulated amortization	$ 557,972	$ 601,013
Patents And Other
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of accumulated amortization	15,192	17,554
Intangible assets, accumulated amortization	42,928	43,021
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Intangible assets, net of accumulated amortization	542,780	583,459
Intangible assets, accumulated amortization	$ 151,007	$ 126,824