Segment, Customer Concentration and Geographical Information - Wireless Revenues by Product (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from External Customer [Line Items]
Total revenues	$ 15,919	$ 12,933	$ 27,300	$ 26,255
Wireless [Member]
Revenue from External Customer [Line Items]
Total revenues	15,919	12,933	27,300	26,255
Wireless [Member] | Family Safety Mobile [Member]
Revenue from External Customer [Line Items]
Total revenues	11,119	7,344	17,385	15,193
Wireless [Member] | CommSuite [Member]
Revenue from External Customer [Line Items]
Total revenues	3,944	4,330	8,073	8,869
Wireless [Member] | ViewSpot [Member]
Revenue from External Customer [Line Items]
Total revenues	817	971	1,746	1,716
Wireless [Member] | Other [Member]
Revenue from External Customer [Line Items]
Total revenues	$ 39	$ 288	$ 96	$ 477