Accounting for Leases as a Lessee - Narrative (Details) $ in Millions	3 Months Ended	6 Months Ended
	Apr. 30, 2020 USD ($)	Apr. 30, 2020 USD ($)
Leases [Abstract]
Net gain from sale and leaseback transaction	$ 0	$ 40
Amount of operating leases that have not yet commenced	$ 210	$ 210
Minimum
Lessee, Lease, Description [Line Items]
Term of operating leases not yet commenced	1 year	1 year
Maximum
Lessee, Lease, Description [Line Items]
Term of operating leases not yet commenced	15 years	15 years