Employee Incentive Plans - Schedule of Common Stock Reserved for Future Issuance (Details)	Apr. 30, 2018 shares
Class of Stock [Line Items]
Common stock reserved for future issuance and options and unvested RSUs outstanding (in shares)	43,771,735
Stock Options And Restricted Stock Units
Class of Stock [Line Items]
Stock options and unvested RSUs outstanding (in shares)	26,108,047
Common stock, reserved for future issuance (in shares)	14,193,351
ESPP
Class of Stock [Line Items]
Common stock, reserved for future issuance (in shares)	3,470,337