Quarterly Financial Data (Unaudited) - Summarized Quarterly Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 12,416	$ 12,629	$ 12,933	$ 13,322	$ 12,278	$ 11,782	$ 10,854	$ 8,432	$ 51,300	$ 43,346
Gross profit	10,994	11,303	11,664	12,149	11,252	10,771	9,880	7,516	46,110	39,419
Operating income (loss)	(12)	196	1,377	1,959	3,631	3,480	2,932	62	3,521	10,105
Net income	$ 580	$ 161	$ 1,379	$ 2,045	$ 3,671	$ 3,567	$ 3,436	$ 48	$ 4,165	$ 10,722
Net earnings per share - basic	$ 0.02		$ 0.03	$ 0.05	$ 0.10	$ 0.10	$ 0.11		$ 0.10	$ 0.31
Weighted average shares outstanding - basic	41,262	41,351	41,127	39,482	38,501	36,094	32,068	31,297	40,808	34,513
Net earnings per share - diluted	$ 0.01		$ 0.03	$ 0.05	$ 0.09	$ 0.09	$ 0.10		$ 0.10	$ 0.29
Weighted average shares outstanding - diluted	43,305	43,026	43,079	42,194	41,767	39,472	35,308	31,323	42,764	36,991