Summary of Business and Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Oct. 31, 2019	Jul. 31, 2020	Jul. 31, 2019	Jan. 31, 2020
Summary Of Business And Significant Accounting Policies [Line Items]
Proceeds from employee stock sales to be remitted			$ 280,200,000	$ 48,500,000
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
Interest rate percentage	3.00%
Debt instrument, fair value disclosure			$ 5,000,000.0