Postretirement Benefits - Components of Postretirement Benefits Expense (Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013
Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost for benefits earned during the period	$ 2	$ 5	$ 6	$ 10
Interest on obligation	40	36	79	72
Amortization of cumulative loss	23	32	47	64
Amortization of prior service benefit	0	0	0	0
Premiums on pension insurance	0	1	0	1
Expected return on assets	(48)	(47)	(96)	(94)
Net postretirement benefits expense	17	27	36	53
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost for benefits earned during the period	1	2	2	4
Interest on obligation	17	16	34	31
Amortization of cumulative loss	4	8	8	15
Amortization of prior service benefit	(1)	(1)	(2)	(2)
Premiums on pension insurance	0	0	0	0
Expected return on assets	(8)	(9)	(16)	(17)
Net postretirement benefits expense	$ 13	$ 16	$ 26	$ 31