Net Loss per Share - Schedule of Basic and Diluted Earnings (Loss) Per Share (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Apr. 30, 2019
Apr. 30, 2018
Numerator:    
Net loss $ (33,240) $ (26,555)
Denominator:    
Weighted-average shares used to compute net loss per share, basic and diluted (in shares) 54,710,746 50,350,052
Net loss per share, basic and diluted (in dollars per share) $ (0.61) $ (0.53)