Segment, Customer Concentration and Geographical Information - Wireless Revenues by Product (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue from External Customer [Line Items]
Total revenues	$ 16,443	$ 12,629	$ 43,743	$ 38,883
Wireless [Member]
Revenue from External Customer [Line Items]
Total revenues	16,443	12,629	43,743	38,883
Wireless [Member] | Family Safety Mobile [Member]
Revenue from External Customer [Line Items]
Total revenues	11,969	6,755	29,355	21,948
Wireless [Member] | CommSuite [Member]
Revenue from External Customer [Line Items]
Total revenues	3,463	4,542	11,535	13,411
Wireless [Member] | ViewSpot [Member]
Revenue from External Customer [Line Items]
Total revenues	971	1,157	2,717	2,873
Wireless [Member] | Other [Member]
Revenue from External Customer [Line Items]
Total revenues	$ 40	$ 175	$ 136	$ 651