Quarterly Financial Data (unaudited) - Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Selected Quarterly Financial Information [Abstract]
Total revenues	$ 37,839	$ 34,306	$ 28,433	$ 23,286	$ 18,821	$ 17,868	$ 14,162	$ 12,703	$ 123,864	$ 63,554	$ 54,515
Gross profit	23,813	21,244	15,992	12,340	9,191	10,579	7,202	5,517	73,389	32,489	27,049
Net income (loss)	$ 4,695	$ 1,043	$ (2,226)	$ (5,539)	$ 6,134	$ (1,936)	$ (4,520)	$ (6,193)	$ (2,027)	$ (6,515)	$ (16,743)
Net income (loss) per common share	$ 0.03	$ 0.01	$ (0.01)	$ (0.03)	$ 0.04	$ (0.01)	$ (0.03)	$ (0.04)
Weighted average shares, basic	163,952	163,119	162,734	160,446	158,389	157,471	157,024	156,724
Weighted average shares, diluted	171,238	168,503	162,734	160,446	162,810	157,471	157,024	156,724