CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	$ 2,092	$ 1,772
Cost of revenue
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	119	28
Sales and marketing
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	154	15
Research and development
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	242	362
General and administrative
Includes stock-based compensation expense as follows:
Total stock-based compensation expense	$ 1,577	$ 1,367