Stock-Based Compensation and Equity - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 977	$ 338	$ 1,834	$ 542
Operating expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	52	26	95	44
Selling expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	82	81	169	126
General and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation	$ 843	$ 231	$ 1,570	$ 372