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	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Earnings Per Share [Abstract]
Net loss	$ (63,459)	$ (49,120)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	189,283	32,605
Net loss per share attributable to common stockholders, basic and diluted	$ (0.34)	$ (1.51)