Segment, Customer Concentration and Geographical Information - Company's Customers that Represent 10% or More of Company's Revenues (Detail) - Revenues [Member] - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue, Major Customer [Line Items]
Customer concentrating on 10% or more of revenue	75.00%	77.00%	76.00%
Wireless [Member] | Sprint and Affiliates [Member]
Revenue, Major Customer [Line Items]
Customer concentrating on 10% or more of revenue	61.00%	63.00%	65.00%
Graphics [Member] | FastSpring [Member]
Revenue, Major Customer [Line Items]
Customer concentrating on 10% or more of revenue	14.00%	14.00%	11.00%