CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	$ 3,748	$ 3,597
Cost of revenue
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	140	305
Sales and marketing
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	469	390
Research and development
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	628	273
General and administrative
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	$ 2,511	$ 2,629