Stockholders’ Equity and Equity Incentive Plan - Additional Information (Details)		1 Months Ended	3 Months Ended		6 Months Ended
	Oct. 31, 2019	Apr. 30, 2019 USD ($) shares	Apr. 30, 2020 USD ($) dates $ / shares shares	Apr. 30, 2019 shares	Jul. 31, 2019 USD ($) shares	Jan. 31, 2020 $ / shares shares
Class of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares			$ 0.001			$ 0.001
Stock options outstanding (in shares)			13,547,925			16,833,009
Unrecognized stock-based compensation expenses related to outstanding unvested stock options | $			$ 69,000,000.0
Number of offering dates | dates			4
Proceeds from unvested shares of common stock | $			$ 1,100,000		$ 1,200,000
RSUs
Class of Stock [Line Items]
Unrecognized stock-based compensation excepted to be recognized over a weighted-average period	3 years 6 months
Unrecognized stock-based compensation expenses | $			$ 179,400,000
Shares vested on the grant date (in shares)			37,518
Employee Stock Purchase Plan
Class of Stock [Line Items]
Unrecognized stock-based compensation excepted to be recognized over a weighted-average period	1 year 1 month 6 days
Unrecognized stock-based compensation expenses | $			$ 48,200,000
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 7 months 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		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
Common stock, capital shares reserved for future issuance, charitable donation (in shares)			6,844	500,000
Common stock, shares reserved for charitable donations, fair value, amount | $			$ 1,000,000.0
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)			490,268
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) | $ / shares			$ 0.001
Class B Common Stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)			300,000,000			300,000,000
Number of common stock subject to repurchase (in shares)			408,662		466,819
Weighted average price per share (in dollars per share) | $ / shares			$ 2.60			$ 2.58
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) | $ / shares			$ 0.001