Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			$ 40
Defined Contribution Plan, Cost Recognized	$ 7	$ 7	22	$ 24
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	20	$ 11	60	$ 73
Effect of change in estimate approach on interest cost	9		27
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect of change in estimate approach on interest cost	$ 4		$ 12