Net Loss per Share Attributable to Common Stockholders - Schedule of Basic and Diluted Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Earnings Per Share [Abstract]
Net loss attributable to common stockholders	$ (24,216)	$ (19,535)	$ (69,985)	$ (64,861)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	17,421,642	12,418,879	14,749,500	11,983,324
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (1.39)	$ (1.57)	$ (4.74)	$ (5.41)