Convertible Preferred Stock, Stockholders’ Equity (Deficit) and Equity Incentive Plan - Summary of Restricted Stock Units Activity Under Equity Incentive Plan (Details) - RSUs	9 Months Ended
	Oct. 31, 2019 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance (in units) | shares	0
Granted (in units) | shares	1,699,579
Cancelled/forfeited (in units) | shares	(16,019)
Ending balance (in units) | shares	1,683,560
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning balance (in dollars per unit) | $ / shares	$ 0
Granted (in dollars per unit) | $ / shares	81.45
Cancelled/forfeited (in dollars per unit) | $ / shares	88.40
Ending balance (in dollars per unit) | $ / shares	$ 81.38