Classification of Compensation Expense Associated with Share-Based Payments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 770	$ 604	$ 1,974	$ 1,862
Cost of Revenue
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated Share-based Compensation Expense	94	127	229	289
Sales and Marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated Share-based Compensation Expense	173	134	411	368
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated Share-based Compensation Expense	442	258	1,167	932
Engineering and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 61	$ 85	$ 167	$ 273