Stockholders' Equity and Stock-Based Compensation - Non-cash Stock-Based Compensation Resulting from Employee Restricted Common Stock Agreements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Non-cash stock-based compensation expense	$ 22,471	$ 3,219	$ 712
Operating Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Non-cash stock-based compensation expense	2,217	235	32
Sales and Marketing Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Non-cash stock-based compensation expense	3,656	559	166
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Non-cash stock-based compensation expense	836	104	16
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Non-cash stock-based compensation expense	$ 15,837	$ 2,112	$ 498