Goodwill and Intangible Assets - Intangible Assets - Finite Life (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Cost	$ 88,050	$ 84,180
Accumulated Amortization	50,417	48,221
Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	14,457	14,457
Accumulated Amortization	9,674	9,414
Customer Lists [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	68,943	68,943
Accumulated Amortization	39,611	37,873
Non-compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	910	910
Accumulated Amortization	799	762
Tradename [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	5,294	1,390
Accumulated Amortization	712	579
Foreign Currency Adjustments [Member]
Finite-Lived Intangible Assets [Line Items]
Cost	(1,554)	(1,520)
Accumulated Amortization	$ (379)	$ (407)