Revenues - Schedule of Revenues on Disaggregated Basis (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Revenues	$ 7,352	$ 6,525	$ 6,945	$ 5,463	$ 5,732	$ 5,804	$ 5,862	$ 5,576	$ 26,285	$ 22,974
Wireless [Member]
Disaggregation Of Revenue [Line Items]
Revenues									24,474	18,342
Wireless [Member] | CommSuite & Netwise [Member]
Disaggregation Of Revenue [Line Items]
Revenues									18,889	14,521
Wireless [Member] | SafePath [Member]
Disaggregation Of Revenue [Line Items]
Revenues									3,327	182
Wireless [Member] | Consulting Services and Other [Member]
Disaggregation Of Revenue [Line Items]
Revenues									1,896	3,355
Wireless [Member] | Legacy Software Licenses [Member]
Disaggregation Of Revenue [Line Items]
Revenues									362	284
Graphics [Member]
Disaggregation Of Revenue [Line Items]
Revenues									1,811	4,632
Graphics [Member] | Software [Member]
Disaggregation Of Revenue [Line Items]
Revenues									$ 1,811	$ 4,632