Etratech Acquisition - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended
	Nov. 01, 2017	Mar. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill		$ 70,439	$ 69,685
Etratech Inc.
Business Acquisition [Line Items]
Product revenues		15,186
Net loss		300
Net assets acquired	$ 65,009
Cash acquired on acquisition	670
Gross contractual amount due of accounts receivable	12,654
Goodwill	14,881
Goodwill not deductible for income taxes	8,651
Intangible assets before foreign currency adjustment	$ 33,362
Fluctuations in foreign currency exchange rates that reduced intangible assets value		390
Amortization of intangibles		$ 958