Consolidated Statements of Operations Information for Each of Previous Eight Quarters (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information [Line Items]
Revenue	$ 69,474	$ 69,445	$ 70,692	$ 60,634	$ 51,942	$ 49,529	$ 47,731	$ 44,830	$ 270,245	$ 194,032	$ 141,236
Gross profit	39,353	38,020	39,984	33,789	28,350	27,346	26,643	25,162
Operating expenses	63,580	61,481	59,638	49,463	44,089	41,643	43,458	38,854
Net income	$ 3,604	$ 1,659	$ 8,095	$ 8,053	$ 5,638	$ 4,794	$ 2,738	$ 3,448	$ 21,411	$ 16,617	$ 28,353
Earnings per share
Basic	$ 0.07	$ 0.03	$ 0.17	$ 0.18	$ 0.13	$ 0.11	$ 0.06	$ 0.08	$ 0.44	$ 0.38	$ 0.74
Diluted	$ 0.07	$ 0.03	$ 0.17	$ 0.17	$ 0.12	$ 0.10	$ 0.06	$ 0.08	$ 0.44	$ 0.37	$ 0.72