CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Stock-based compensation expense	$ 292,257	$ 214,179	$ 69,368
Cost of revenues
Stock-based compensation expense	26,057	17,189	5,283
Research and development
Stock-based compensation expense	89,197	60,777	20,829
Sales and marketing
Stock-based compensation expense	130,054	90,064	30,012
General and administrative
Stock-based compensation expense	$ 46,949	$ 46,149	$ 13,244