Postretirement Benefits - Schedule of Net Benefit (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2015	Jul. 31, 2014
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 3	$ 3	$ 9	$ 9
Interest on obligations	35	39	106	118
Amortization of cumulative loss	25	23	74	70
Amortization of cumulative loss	0	0	0	0
Contractual termination benefits	0	14	(1)	14
Premiums on pension insurance	3	0	8	0
Expected return on assets	(48)	(48)	(145)	(144)
Net postretirement benefits expense	18	31	51	67
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	5	4
Interest on obligations	17	17	53	51
Amortization of cumulative loss	10	4	29	12
Amortization of cumulative loss	(1)	(1)	(3)	(3)
Contractual termination benefits	0	0	(1)	0
Premiums on pension insurance	0	0	0	0
Expected return on assets	(7)	(8)	(22)	(24)
Net postretirement benefits expense	$ 21	$ 14	$ 61	$ 40