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		9 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Earnings Per Share [Abstract]
Net loss	$ (56,501)	$ (40,397)	$ (169,458)	$ (135,596)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	74,565	28,280	47,109	26,769
Net loss per share attributable to common stockholders, basic and diluted	$ (0.76)	$ (1.43)	$ (3.60)	$ (5.07)