Goodwill and Intangible Assets - Components of Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Acquired Finite Lived Intangible Assets [Line Items]
Finite lived intangible assets, Cost	$ 139,784	$ 139,784
Finite lived intangible assets, Accumulated amortization	(50,270)	(40,445)
Finite lived intangible assets, Net	89,514	99,339
Customer Lists [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Finite lived intangible assets, Cost	113,357	113,357
Finite lived intangible assets, Accumulated amortization	(37,300)	(29,451)
Finite lived intangible assets, Net	$ 76,057	83,906
Customer Lists [Member] | Minimum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Useful life (years)	5 years
Customer Lists [Member] | Maximum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Useful life (years)	15 years
Patents and Technology [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Finite lived intangible assets, Cost	$ 23,424	23,424
Finite lived intangible assets, Accumulated amortization	(9,977)	(8,080)
Finite lived intangible assets, Net	$ 13,447	15,344
Patents and Technology [Member] | Minimum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Useful life (years)	5 years
Patents and Technology [Member] | Maximum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Useful life (years)	10 years
Trade Names and Trademarks [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Finite lived intangible assets, Cost	$ 3,003	3,003
Finite lived intangible assets, Accumulated amortization	(2,993)	(2,914)
Finite lived intangible assets, Net	$ 10	$ 89
Trade Names and Trademarks [Member] | Minimum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Useful life (years)	1 year
Trade Names and Trademarks [Member] | Maximum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Useful life (years)	2 years