Etratech Acquisition - Summary of Property and Equipment (Detail) - Etratech Inc. - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Nov. 01, 2017
Property Plant And Equipment [Line Items]
Property and equipment		$ 6,205
Leasehold improvements
Property Plant And Equipment [Line Items]
Property and equipment, Useful life	10 years
Property and equipment	$ 342
Machinery and equipment
Property Plant And Equipment [Line Items]
Property and equipment	$ 5,248
Machinery and equipment | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, Useful life	4 years
Machinery and equipment | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, Useful life	11 years
Furniture and fittings
Property Plant And Equipment [Line Items]
Property and equipment, Useful life	4 years
Property and equipment	$ 230
Motor vehicles
Property Plant And Equipment [Line Items]
Property and equipment, Useful life	3 years
Property and equipment	$ 25
Computer hardware and software
Property Plant And Equipment [Line Items]
Property and equipment, Useful life	1 year
Property and equipment	$ 360