Goodwill and Intangible Assets - Intangible Assets - Finite Life (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Cost	$ 88,360	$ 94,658
Accumulated Amortization	45,916	44,702
Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	14,457	15,867
Accumulated Amortization	8,553	8,609
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	72,978	77,497
Accumulated Amortization	36,328	35,024
Non-compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	1,118	1,118
Accumulated Amortization	809	698
Tradename [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	1,390	1,390
Accumulated Amortization	510	440
Foreign Currency Adjustments [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	(1,583)	(1,214)
Accumulated Amortization	$ (284)	$ (69)