Summary of Significant Accounting Policies - Product Warranty Liability (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017	Oct. 31, 2017	Oct. 31, 2016
Product Liability Contingency [Line Items]
Document Type			10-Q
Product Warranty Accrual	$ 531	$ 659	$ 531	$ 659	$ 629	$ 818
Product Warranty Accrual, Warranties Issued			139	137
Accrued Product Warranty And Deferred Warranty Revenue, Standard And Extended Warranty Programs, Roll Forward:
Adjustments to pre-existing warranties(A)(B)			(4)	(4)
Extended Warranty Program:
Product Warranty Accrual, Payments			(233)	(292)
Product Warranty Accrual, Current	254	340	254	340
Product Warranty Accrual, Noncurrent	277	319	277	319
Extended Warranty Programs [Member]
Extended Warranty Program:
Deferred Revenue, Revenue Recognized	24	$ 28	80	$ 109
Deferred Revenue	$ 248		$ 248		$ 271