Components of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets by Major Class [Line Items]
Definite-lived intangibles, gross amount	$ 472,268	$ 210,003
Intangibles, gross amount	504,408	242,143
Definite-lived intangibles, accumulated amortization	(87,320)	(61,361)
Trade names [Member]
Intangible Assets by Major Class [Line Items]
Indefinite-lived intangibles, gross amount	32,140	32,140
Customer relationships [Member]
Intangible Assets by Major Class [Line Items]
Definite-lived intangibles, gross amount	430,730	195,076
Definite-lived intangibles, accumulated amortization	(74,469)	(53,298)
Other definite-lived intangibles [Member]
Intangible Assets by Major Class [Line Items]
Definite-lived intangibles, gross amount	41,538	14,927
Definite-lived intangibles, accumulated amortization	$ (12,851)	$ (8,063)