Organization and Summary of Significant Accounting Policies - Net Sales by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales by geographic area	$ 94,651	$ 90,262	$ 79,643	$ 79,242	$ 82,077	$ 71,882	$ 58,756	$ 55,530	$ 343,798	$ 268,245	$ 197,892
Percentage of net sales by geographic area									100.00%	100.00%	100.00%
United States
Segment Reporting Information [Line Items]
Net sales by geographic area									$ 282,810	$ 218,757	$ 161,803
Percentage of net sales by geographic area									82.30%	81.60%	81.80%
Other Countries
Segment Reporting Information [Line Items]
Net sales by geographic area									$ 60,988	$ 49,488	$ 36,089
Percentage of net sales by geographic area									17.70%	18.40%	18.20%