Significant Accounting Policies - Additional Information (Detail)		12 Months Ended
	Jan. 01, 2017	Dec. 31, 2016 USD ($) Customer	Dec. 31, 2015 USD ($) Customer	Dec. 31, 2014 USD ($) Customer
Revenue, Major Customer [Line Items]
Gross deferred revenue		$ 3,337,000	$ 2,042,000
Gross deferred cost of revenue		$ 1,445,000	$ 882,000
Revenue recognized under multi-element		3.00%	3.00%	3.00%
Foreign currency losses, net		$ (268,000)	$ (161,000)	$ (196,000)
Maturity period of cash and cash equivalents		Less than three months
Available-for-sale securities, failed auction, value		$ 3,000,000
Number of customers accounted for trade account receivable | Customer		1	1
Number of customers | Customer		1	1	1
Cost of advertising		$ 1,818,000	$ 1,762,000	$ 1,832,000
Product warranty period		2 years
Percentage likelihood of tax benefit settlement		50.00%
Recognition period of non performance based stock options		5 years
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Percentage of total net revenues		16.40%	16.20%	14.70%
Sales Revenue, Net [Member] | Geographic Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Percentage of total net revenues		59.40%	59.60%	60.50%
Sales Revenue, Net [Member] | China [Member] | Geographic Concentration Risk [Member]
Revenue, Major Customer [Line Items]
Percentage of total net revenues		32.10%	34.20%	32.30%
Military Grade Products [Member] | Subsequent Event [Member]
Revenue, Major Customer [Line Items]
Extended warranty period	3 years
Customer One [Member]
Revenue, Major Customer [Line Items]
Percentage of trade account receivable		14.20%	21.90%
Maximum [Member]
Revenue, Major Customer [Line Items]
Recognition period		12 months
Estimated useful life of intangible assets		20 years
Minimum [Member]
Revenue, Major Customer [Line Items]
Recognition period		6 months
Estimated useful life of intangible assets		3 years