Segment, Customer Concentration and Geographical Information - Revenues Generated by Each Business Unit (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue from External Customer [Line Items]
Total revenues	$ 5,804	$ 6,478	$ 17,242	$ 21,151
Wireless [Member]
Revenue from External Customer [Line Items]
Total revenues	4,690	5,237	13,678	17,513
Graphics [Member]
Revenue from External Customer [Line Items]
Total revenues	$ 1,114	$ 1,241	$ 3,564	$ 3,638