Net Loss per Share Attributable to Common Stockholders - 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, 2017	Jan. 31, 2016	Jan. 31, 2015
Numerator:
Net loss attributable to common stockholders	$ (37,607)	$ (46,156)	$ (27,300)
Denominator:
Weighted-average number of shares used in computing net loss per share attributable to common stockholders, basic and diluted	19,988	4,704	2,999
Net loss per share attributable to common stockholders, basic and diluted	$ (1.88)	$ (9.81)	$ (9.10)