Postretirement Benefits - Schedule of Net Benefit (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 7	$ 7	$ 25	$ 22
Employer contributions	25	21	78	67
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment		2
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2	5	6
Interest on obligations	27	27	81	80
Amortization of cumulative loss	26	30	79	89
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	23	9	23
Contractual termination benefits	0	9	0	10
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	0	0	0	0
Premiums on pension insurance	1	4	3	12
Expected return on assets	(40)	(40)	(121)	(119)
Net postretirement benefits expense	15	55	56	101
Health and Life Insurance Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	4
Interest on obligations	10	11	32	35
Amortization of cumulative loss	3	6	7	17
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0	0
Contractual termination benefits	0	4	0	4
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	0	58	0	58
Premiums on pension insurance	0	0	0	0
Expected return on assets	(5)	(5)	(17)	(17)
Net postretirement benefits expense	$ 9	$ (41)	$ 25	$ (15)