Net Loss Per Share - Schedule of Antidilutive Securities Excluded from the Computation of Diluted Net Loss per Share (Details) - shares	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Stock options to purchase common stock | Class A Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,234,642	2,042,636	1,434,388	2,242,253
Stock options to purchase common stock | Class B Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3,614,730	4,805,226	4,013,050	5,230,288
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3,871,174	2,876,802	3,925,426	2,790,999
Early exercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	2,831	22,940	6,418	33,900
Shares underlying the conversion spread in the convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	925,870	2,171,371	841,126	2,175,450