Condensed Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Recognized stock-based compensation expense	$ 4,648	$ 8,553	$ 22,541	$ 26,942
Cost of Revenue [Member]
Recognized stock-based compensation expense	486	642	1,985	1,873
Research and Development [Member]
Recognized stock-based compensation expense	1,640	2,061	7,556	6,987
Sales and Marketing [Member]
Recognized stock-based compensation expense	1,108	2,260	5,176	6,159
General and Administrative [Member]
Recognized stock-based compensation expense	$ 1,414	$ 3,590	$ 7,824	$ 11,923