Postretirement Benefits - Schedule of Net Benefit (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2016	Jul. 31, 2015
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 3	$ 7	$ 9
Interest on obligations	29	35	88	106
Amortization of cumulative loss	26	25	78	74
Amortization of cumulative loss	0	0	0	0
Contractual termination benefits	1	0	3	(1)
Premiums on pension insurance	4	3	12	8
Expected return on assets	(41)	(48)	(125)	(145)
Net postretirement benefits expense	21	18	63	51
Health and Life Insurance Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2	4	5
Interest on obligations	14	17	44	53
Amortization of cumulative loss	8	10	24	29
Amortization of cumulative loss	0	(1)	(1)	(3)
Contractual termination benefits	4	0	4	(1)
Premiums on pension insurance	0	0	0	0
Expected return on assets	(6)	(7)	(19)	(22)
Net postretirement benefits expense	$ 21	$ 21	$ 56	$ 61