Balance Sheet Information - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Allowance for doubtful accounts	$ 0.2		$ 0.2		$ 0.2
Consigned inventory with customers	1.7		1.7		1.2
Allowance for inventory losses	1.9		1.9		2.0
Depreciation and amortization expense	$ 0.7	$ 0.6	$ 2.0	$ 1.8
Building [Member]
Property, Plant and Equipment [Line Items]
Useful lives of the assets			30 years
Office equipment [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are deprecated			5 years
Manufacturing and test equipment [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are deprecated			5 years
Motor vehicles [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are deprecated			5 years
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are deprecated			7 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Standard term of accounts receivable			60 days
Useful lives of the assets			1 year
Maximum [Member] | Computer equipment [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are deprecated			5 years
Minimum [Member]
Property, Plant and Equipment [Line Items]
Standard term of accounts receivable			30 days
Minimum [Member] | Computer equipment [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are deprecated			3 years