Postretirement Benefits - Schedule of Net Benefit (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost Recognized	$ 7	$ 7	$ 22	$ 22
Employer contributions	21	20	67	60
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	6	7
Interest on obligations	27	29	80	88
Amortization of cumulative loss	30	26	89	78
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	23	0	23	0
Contractual termination benefits	9	1	10	3
Curtailments and other	0	0	0	0
Premiums on pension insurance	4	4	12	12
Expected return on assets	(40)	(41)	(119)	(125)
Net postretirement benefits expense	55	21	101	63
Health and Life Insurance Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	4	4
Interest on obligations	11	14	35	44
Amortization of cumulative loss	6	8	17	24
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0	(1)
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	0	0	0
Contractual termination benefits	4	4	4	4
Curtailments and other	(58)	0	(58)	0
Premiums on pension insurance	0	0	0	0
Expected return on assets	(5)	(6)	(17)	(19)
Net postretirement benefits expense	$ (41)	$ 21	$ (15)	$ 56