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		6 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015
Numerator:
Net loss	$ (38,102)	$ (50,175)	$ (76,677)	$ (97,458)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	126,776	120,399	125,864	119,987
Net loss per share—basic and diluted	$ (0.30)	$ (0.42)	$ (0.61)	$ (0.81)
Class A Common Stock
Numerator:
Net loss	$ (15,305)	$ (9,391)	$ (28,983)	$ (15,396)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	50,925	22,535	47,575	18,941
Net loss per share—basic and diluted	$ (0.30)	$ (0.42)	$ (0.61)	$ (0.81)
Class B Common Stock
Numerator:
Net loss	$ (22,797)	$ (40,784)	$ (47,694)	$ (82,062)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	75,851	97,864	78,289	100,956
Net loss per share—basic and diluted	$ (0.30)	$ (0.42)	$ (0.61)	$ (0.81)