Revenue Recognition - Schedule of Disaggregated Revenue By Major Product Line in Single Reporting Segment (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
Disaggregation Of Revenue [Line Items]
Total	$ 5,553	$ 5,751	$ 6,497	$ 6,189	$ 5,319	$ 5,828	$ 6,180	$ 5,660	$ 23,990	$ 22,987
Service [Member]
Disaggregation Of Revenue [Line Items]
Total	2,899	3,352	3,892	3,738	2,700	3,160	3,575	3,814	13,881	13,249
Subscription [Member]
Disaggregation Of Revenue [Line Items]
Total	$ 2,654	$ 2,399	$ 2,605	$ 2,451	$ 2,619	$ 2,668	$ 2,605	$ 1,846	10,109	9,738
Government [Member]
Disaggregation Of Revenue [Line Items]
Total									14,946	14,311
Government [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total									13,263	12,793
Government [Member] | Subscription [Member]
Disaggregation Of Revenue [Line Items]
Total									1,683	1,518
Retail [Member]
Disaggregation Of Revenue [Line Items]
Total									5,560	5,258
Retail [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total									618	456
Retail [Member] | Subscription [Member]
Disaggregation Of Revenue [Line Items]
Total									4,942	4,802
Media [Member]
Disaggregation Of Revenue [Line Items]
Total									3,484	3,418
Media [Member] | Service [Member]
Disaggregation Of Revenue [Line Items]
Total									0	0
Media [Member] | Subscription [Member]
Disaggregation Of Revenue [Line Items]
Total									$ 3,484	$ 3,418