Equity Incentive Plans - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jul. 31, 2020 USD ($) $ / shares shares	Jan. 31, 2020 USD ($) $ / shares shares
Number of Shares
Options outstanding, beginning balance (in shares) | shares	41,935,173
Options exercised (in shares) | shares	(9,853,483)
Options cancelled or expired (in shares) | shares	(569,330)
Options outstanding, ending balance (in shares) | shares	31,512,360	41,935,173
Options exercisable (in shares) | shares	20,217,598
Average Exercise Price per Share
Options outstanding, beginning balance, average exercise price (in usd per share) | $ / shares	$ 5.47
Options exercised, weighted average exercise price (in usd per share) | $ / shares	4.13
Options cancelled or expired, weighted average exercise price (in usd per share) | $ / shares	6.71
Options outstanding, ending balance, average exercise price (in usd per share) | $ / shares	5.87	$ 5.47
Options exercisable, average exercise price (in usd per share) | $ / shares	$ 5.48
Weighted average remaining contractual term, options outstanding	7 years 2 months 12 days	7 years 3 months 14 days
Weighted average remaining contractual term, options exercisable	6 years 9 months
Aggregate intrinsic value, options outstanding | $	$ 954,124
Aggregate intrinsic value, exercises in period | $	262,410
Aggregate intrinsic value, options outstanding | $	783,580	$ 954,124
Aggregate intrinsic value, options exercisable | $	$ 510,437