Postretirement Benefits - Amounts Recognized in Balance Sheet and in Accumulated Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2011
Amounts recognized in our Consolidated Balance Sheets consist of:
Noncurrent liability	$ 2,564	$ 3,405
Net liability recognized	2,652	3,511
Pension Plan, Defined Benefit [Member]
Amounts recognized in our Consolidated Balance Sheets consist of:
Current liability	14	14
Noncurrent liability	1,410	2,067
Net liability recognized	1,424	2,081
Amounts recognized in our accumulated other comprehensive loss consist of:	(585)	357	267
Net actuarial loss	(1,947)	(2,529)
Net prior service cost (benefit)	1	3
Net amount recognized	1,948	2,532
Other Postretirement Benefit Plan, Defined Benefit [Member]
Amounts recognized in our Consolidated Balance Sheets consist of:
Current liability	73	92
Noncurrent liability	1,154	1,337
Net liability recognized	1,227	1,429
Amounts recognized in our accumulated other comprehensive loss consist of:	(200)	(88)	893
Net actuarial loss	(354)	(558)
Net prior service cost (benefit)	(10)	(13)
Net amount recognized	$ 344	$ 545