Financing Receivables and Operating Leases - Allowance for Doubtful Accounts for Financing Receivables (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Jul. 31, 2017	Oct. 31, 2016
Allowance for doubtful accounts
Balance at beginning of period	$ 89	$ 95
Provision for doubtful accounts	17	11
Write-offs	(16)	(17)
Balance at end of period	$ 90	$ 89