Postretirement benefits (Components of Net Periodic Benefit Expense (Income)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011	Oct. 31, 1993 Other Pension Plans, Postretirement or Supplemental Plans, Defined Benefit [Member]	Jul. 31, 2012 Pension Benefit [Member]	Jul. 31, 2011 Pension Benefit [Member]	Jul. 31, 2012 Pension Benefit [Member]	Jul. 31, 2011 Pension Benefit [Member]	Jul. 31, 2012 Health and Life Insurance Benefits [Member]	Jul. 31, 2011 Health and Life Insurance Benefits [Member]	Jul. 31, 2012 Health and Life Insurance Benefits [Member]	Jul. 31, 2011 Health and Life Insurance Benefits [Member]	Jan. 31, 2011 Pension And Other Postretirement Contractual Termination Benefits [Member] Truck [Member] Location Fort Wayne [Member]
Defined Benefit Plan Disclosure [Line Items]
Profit Sharing Accruals					$ 0
Defined Benefit Plan, Benefits Paid	30						28	112	80
Restructuring Charges	4	56	24	80										5
Defined Contribution Plan, Cost Recognized	8	7	32	25
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost for benefits earned during the period						5	4	13	13	1	2	5	6
Interest on obligations						43	47	129	141	20	13	62	40
Amortization of cumulative loss						27	25	82	75	10	0	30	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)						1	1	1	1	(2)	(7)	(4)	(22)
Defined Benefit Plan, Curtailments						0	0	0	2	0	11	0	11
Contractual termination benefits						0	35	0	38	0	6	(3)	6
Premium on Pension Insurance						0	0	1	1	0	0	0	0
Expected return on assets						(49)	(53)	(145)	(158)	(8)	(10)	(26)	(31)
Net postretirement benefits expense (income)						$ 27	$ 59	$ 81	$ 113	$ 21	$ 15	$ 64	$ 10