Net Loss per Share - Schedule of Potentially Dilutive Securities Excluded from Computation of Net Loss per Share (Details) - shares	9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	58,474,868	78,507,510
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	47,781,688	69,634,367
Shares subject to repurchase
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	537,188	1,171,124
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	10,115,953	7,616,097
Employee stock purchase rights under the 2020 ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted net loss per share (in shares)	40,039	85,922