Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Net intangible assets	$ 80,736	$ 82,511
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	118,916	118,223
Accumulated amortization	(40,902)	(38,429)
Net intangible assets	78,014	79,794
Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	4,102	4,045
Accumulated amortization	(1,380)	(1,328)
Net intangible assets	$ 2,722	$ 2,717