Net Loss per Share Attributable to Common Stockholders - Summary of Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Earnings Per Share [Abstract]
Net loss	$ (213,752)	$ (183,231)	$ (78,561)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	82,460	27,925	24,237
Net loss per share attributable to common stockholders, basic and diluted	$ (2.59)	$ (6.56)	$ (3.24)