Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
Numerator:
Net loss	$ (57,662)	$ (51,966)
Denominator:
Weighted-average shares outstanding - basic and diluted (in shares)	123,494	112,682
Net loss per share, basic and diluted (in dollars per share)	$ (0.47)	$ (0.46)
Class A Common Stock
Numerator:
Net loss	$ (53,684)	$ (47,227)
Denominator:
Weighted-average shares outstanding - basic and diluted (in shares)	114,975	102,407
Net loss per share, basic and diluted (in dollars per share)	$ (0.47)	$ (0.46)
Class B Common Stock
Numerator:
Net loss	$ (3,978)	$ (4,739)
Denominator:
Weighted-average shares outstanding - basic and diluted (in shares)	8,519	10,275
Net loss per share, basic and diluted (in dollars per share)	$ (0.47)	$ (0.46)