Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Net intangible assets	$ 178,880	$ 184,468
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	200,574	199,265
Accumulated amortization	(60,641)	(54,757)
Net intangible assets	139,933	144,508
Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	43,683	43,537
Accumulated amortization	(4,736)	(3,577)
Net intangible assets	$ 38,947	$ 39,960