Net Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Earnings Per Share [Abstract]
Net loss	$ (100,336)	$ (64,304)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	245,334	223,768
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.41)	$ (0.29)