Net Loss Per Share - Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
3 Months Ended
Apr. 30, 2019
Apr. 30, 2018
Numerator:    
Net loss $ (12,064) $ (6,579)
Denominator:    
Weighted-average shares used in calculating net loss per share, basic and diluted (in shares) 32,510 20,878
Net loss per share, basic and diluted (in dollars per share) $ (0.37) $ (0.32)