Balance Sheet Information - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Allowance for doubtful accounts	$ 302		$ 302		$ 273
Consigned inventory with customers	700		700		400
Allowance for inventory losses	3,200		3,200		$ 2,900
Depreciation and amortization expense in continuing operations	$ 700	$ 700	$ 1,900	$ 2,000
Equipment [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are depreciated			5 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are depreciated			7 years
Building [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are depreciated			30 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 depreciated			3 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Standard term of accounts receivable			90 days
Useful lives of the assets			1 year
Maximum [Member] | Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Period over which assets are depreciated			5 years