Stockholders’ Equity and Equity Incentive Plans - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2020	Apr. 30, 2019	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Jan. 31, 2020
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.001		$ 0.001		$ 0.001		$ 0.001
Stock options outstanding (in shares)	10,478,169		10,478,169		10,478,169		16,833,009
Unrecognized stock-based compensation expenses related to outstanding unvested stock options	$ 53,900,000		$ 53,900,000		$ 53,900,000
Proceeds from unvested shares of common stock					800,000		$ 1,200,000
RSUs
Class of Stock [Line Items]
Unrecognized stock-based compensation excepted to be recognized over a weighted-average period	3 years
Unrecognized stock-based compensation expenses	$ 711,300,000		711,300,000		$ 711,300,000
Shares vested on the grant date (in shares)					435,302
Employee Stock Purchase Plan
Class of Stock [Line Items]
Unrecognized stock-based compensation excepted to be recognized over a weighted-average period	7 months 6 days
Unrecognized stock-based compensation expenses	$ 40,800,000		$ 40,800,000		$ 40,800,000
Maximum number of shares per employee (in shares)		3,000
Consecutive offering period		27 months
Share-based Payment Arrangement, Option
Class of Stock [Line Items]
Unrecognized stock-based compensation excepted to be recognized over a weighted-average period	2 years 1 month 6 days
2011 Plan
Class of Stock [Line Items]
Number of shares available for future issuance (in shares)		24,300,889
2019 Plan
Class of Stock [Line Items]
Percentage of shares reserved increase		5.00%
2019 Employee Stock Purchase Plan | Employee Stock Purchase Plan
Class of Stock [Line Items]
Annual increase in shares for available for future issuance by percentage of the outstanding ordinary shares on the first day of such fiscal year.		1.00%
Annual increase in Number of shares of common stock available for future issuance (in shares)		7,500,000
Class A Common Stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	2,000,000,000		2,000,000,000		2,000,000,000		2,000,000,000
Common stock, capital shares reserved for future issuance, charitable donation (in shares)	94,844				500,000
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	405,156		39,872	652,938	200,420	504,483
Class A Common Stock | Held For Charitable Contributions
Class of Stock [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)					23,300,000
Class A Common Stock | Employee Stock Purchase Plan
Class of Stock [Line Items]
Percentage of purchase price of common stock to fair market value of common stock on offering or purchase date		85.00%
ESPP excess rate purchase right, value		$ 25,000
Shares issued of common stock (in shares)					1,096,192
Class A Common Stock | 2019 Plan
Class of Stock [Line Items]
Number of shares available for future issuance (in shares)		58,300,889
Numbers of additional shares authorized under the plan (in shares)		34,000,000
Class A Common Stock | 2019 Employee Stock Purchase Plan | Employee Stock Purchase Plan
Class of Stock [Line Items]
Number of shares available for future issuance (in shares)		9,000,000
Class A Common Stock | Initial public offering
Class of Stock [Line Items]
Common stock, shares authorized (in shares)		2,000,000,000
Common stock, par value (in dollars per share)		$ 0.001
Class B Common Stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	300,000,000		300,000,000		300,000,000		300,000,000
Number of common stock subject to repurchase (in shares)					269,564		466,819
Weighted average price per share (in dollars per share)	$ 2.79		$ 2.79		$ 2.79		$ 2.58
Antidilutive securities excluded from computation of earnings per share, amount (in shares)			0	0		0
Class B Common Stock | Initial public offering
Class of Stock [Line Items]
Common stock, shares authorized (in shares)		300,000,000
Common stock, par value (in dollars per share)		$ 0.001