Segment, Customer Concentration and Geographical Information - Wireless Revenues by Product (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Revenue from External Customer [Line Items]
Total revenues	$ 12,416	$ 12,629	$ 12,933	$ 13,322	$ 12,278	$ 11,782	$ 10,854	$ 8,432	$ 51,300	$ 43,346
Wireless [Member]
Revenue from External Customer [Line Items]
Total revenues									50,671	42,604
Wireless [Member] | CommSuite [Member]
Revenue from External Customer [Line Items]
Total revenues									18,163	18,713
Wireless [Member] | SafePath [Member]
Revenue from External Customer [Line Items]
Total revenues									28,027	17,782
Wireless [Member] | ViewSpot [Member]
Revenue from External Customer [Line Items]
Total revenues									4,239	4,229
Wireless [Member] | Netwise [Member]
Revenue from External Customer [Line Items]
Total revenues									151	1,642
Wireless [Member] | Other [Member]
Revenue from External Customer [Line Items]
Total revenues									$ 91	$ 238