Equity Incentive Plans and Employee Stock Purchase Plan - Schedule of Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Apr. 30, 2020 $ / shares shares
Shares
Unvested - beginning of period (in shares) | shares	3,281,431
RSUs granted (in shares) | shares	1,077,847
RSUs vested (in shares) | shares	(241,569)
RSUs forfeited and canceled (in shares) | shares	(87,213)
Unvested - end of period (in shares) | shares	4,030,496
Weighted-Average Grant Date Fair Value per RSU
Unvested - beginning of period (in dollars per share) | $ / shares	$ 102.30
RSUs granted (in dollars per share) | $ / shares	148.52
RSUs vested (in dollars per share) | $ / shares	86.41
RSUs forfeited and canceled (in dollars per share) | $ / shares	103.95
Unvested - end of period (in dollars per share) | $ / shares	$ 115.58