Stock Incentive Plans - Summary of Expense Relating to Employee and Nonemployee Stock-Based Payment Awards from Stock Options and RSUs (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation total expensed	$ 6,748	$ 5,964	$ 17,424	$ 17,010
Cost of testing services
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation total expensed	431	294	1,101	1,423
Cost of product
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation total expensed	97	77	289	192
Cost of digital and other
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation total expensed	124	54	338	90
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation total expensed	1,224	954	3,490	3,227
Sales and Marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation total expensed	1,623	1,125	4,175	2,796
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation total expensed	$ 3,249	$ 3,460	$ 8,031	$ 9,282