Leases - Supplemental Cash Flow Information (Details) $ in Millions	6 Months Ended
	Apr. 30, 2020 USD ($)
Leases [Abstract]
Cash paid for amount included in the measurement of lease liabilities	$ 123
Right-of-use assets obtained in exchange of lease liabilities	$ 95
Weighted-average remaining lease term in years	7 years
Weighted-average discount rate	2.70%