Net Loss per Share - Summary of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Numerator:
Net loss	$ (40,086)	$ (38,575)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	131,469	124,932
Net loss per share—basic and diluted	$ (0.30)	$ (0.31)
Class A Common Stock
Numerator:
Net loss	$ (22,061)	$ (13,632)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	72,352	44,151
Net loss per share—basic and diluted	$ (0.30)	$ (0.31)
Class B Common Stock
Numerator:
Net loss	$ (18,025)	$ (24,943)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	59,117	80,781
Net loss per share—basic and diluted	$ (0.30)	$ (0.31)