Stock-Based Compensation - Summary Components of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 1,728	$ 1,445	$ 3,435	$ 2,969
Cost of Services [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	144	114	308	273
Cost of Product Sales [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	24	19	63	42
Selling, General and Administrative [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	1,354	1,230	2,646	2,502
Product Development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation	$ 206	$ 82	$ 418	$ 152