CONSOLIDATED STATEMENTS OF OPERATIONS (PARENTHETICAL) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based compensation	$ 85,049	$ 73,779	$ 52,556
Cost of revenue
Share-based compensation	9,040	7,045	4,541
Research and development
Share-based compensation	29,970	27,083	19,414
Sales and marketing
Share-based compensation	24,776	23,043	14,759
General and administrative
Share-based compensation	$ 21,263	$ 16,608	$ 13,842