Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Schedule of Intangible Asset by Major Class [Line Items]
Intangible Assets, Gross Amount (Excluding Goodwill), Total	$ 10,940	$ 10,653
Finite-Lived Intangible Assets, Accumulated Amortization	$ 8,456	7,535
Patents and licenses, software and hardware designs
Schedule of Intangible Asset by Major Class [Line Items]
Weighted Average Life	6 years
Finite-Lived Intangible Assets, Gross Amount	$ 5,320	5,033
Finite-Lived Intangible Assets, Accumulated Amortization	$ 3,540	3,187
Developed technology
Schedule of Intangible Asset by Major Class [Line Items]
Weighted Average Life	10 years
Finite-Lived Intangible Assets, Gross Amount	$ 2,782	2,782
Finite-Lived Intangible Assets, Accumulated Amortization	$ 2,295	2,017
Customer relationships and non-compete
Schedule of Intangible Asset by Major Class [Line Items]
Weighted Average Life	9 years
Finite-Lived Intangible Assets, Gross Amount	$ 2,838	2,838
Finite-Lived Intangible Assets, Accumulated Amortization	$ 2,621	$ 2,331