Summary of Business and Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended
	Apr. 30, 2020	Oct. 31, 2019	Apr. 30, 2019	Jan. 31, 2020
Summary Of Business And Significant Accounting Policies [Line Items]
Proceeds from employee stock sales to be remitted	$ 267,100,000		$ 48,500,000
Proceeds from international employee stock sales to be remitted to employees and tax authorities, net	218,540,000		$ 0
Payments to acquire equity securities without readily determinable fair value	8,000,000.0	$ 3,000,000.0
Unrealized gain (loss) on investments	2,500,000
Equity securities without readily determinable fair value, amount	13,500,000			$ 3,000,000.0
Convertible Promissory Note | Convertible Debt
Summary Of Business And Significant Accounting Policies [Line Items]
Debt instrument face amount	$ 5,000,000.0
Debt instrument term	5 years
Interest rate percentage	3.00%
Debt instrument, fair value disclosure	$ 5,000,000.0