Allowance for Doubtful Accounts Receivable and Sales Returns (Additional Information) (Detail) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2016 USD ($) Customer	Sep. 30, 2015 USD ($) Customer	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 Customer
Concentration Risk [Line Items]
Revenue | $	[1]	$ 31,051	$ 30,823	$ 89,015	$ 95,374
Accounts Receivable | Company A
Concentration Risk [Line Items]
Number of customers		1				1
Percentage by major customer		57.00%				52.00%
Accounts Receivable | Company B
Concentration Risk [Line Items]
Number of customers		1				1
Percentage by major customer		14.00%				12.00%
Revenue by Segment | Mobile Services | Company A
Concentration Risk [Line Items]
Number of customers		1	1
Percentage by major customer		32.00%	28.00%	31.00%	25.00%
Revenue | $		$ 9,900	$ 8,700	$ 27,900	$ 24,200

[1] Quarters Ended September 30,Components of Revenue2016 2015License Fees7,850 7,049Service Revenue23,201 23,774Net Revenue31,051 30,823 Nine Months Ended September 30,Components of Cost of Revenue2016 2015License Fees$20,305 $21,259Service Revenue68,710 74,115Net Revenue$89,015 $95,374