Postretirement Benefits (Details) (USD $)				3 Months Ended	9 Months Ended	12 Months Ended								1 Months Ended	5 Months Ended	12 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012 United States Postretirement Benefit Plans of US Entity, Defined Benefit [Member]	Jul. 31, 2012 Pension Plans, Defined Benefit [Member]	Jul. 31, 2012 Pension Plans, Defined Benefit [Member]	Oct. 31, 2012 Pension Plans, Defined Benefit [Member]		Oct. 31, 2011 Pension Plans, Defined Benefit [Member]		Oct. 31, 2010 Pension Plans, Defined Benefit [Member]		Oct. 31, 2012 Unfunded pension plan [Member]	Oct. 31, 2011 Unfunded pension plan [Member]	Mar. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]	Mar. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]	Oct. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit [Member]		Oct. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member]		Oct. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations at beginning of year					$ 4,171,000,000	$ 4,171,000,000		$ 4,005,000,000								$ 2,000,000,000		$ 1,162,000,000
Defined Benefit Plan, Plan Amendments						0		0								0		302,000,000
Defined Benefit Plan, Service Cost						17,000,000		17,000,000		18,000,000						7,000,000		8,000,000		8,000,000
Defined Benefit Plan, Interest Cost						169,000,000		189,000,000		209,000,000						83,000,000		56,000,000		81,000,000
Defined Benefit Plan, Actuarial Gain (Loss)						462,000,000		242,000,000								(72,000,000)		547,000,000
Defined Benefit Plan, Curtailments						4,000,000		(11,000,000)								0		11,000,000
Defined Benefit Plan, Special Termination Benefits						2,000,000		38,000,000								(3,000,000)		6,000,000
Defined Benefit Plan, Retrospective Payments Due To Retirees																(2,000,000)		15,000,000
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)						(5,000,000)		26,000,000								0		0
Defined Benefit Plan, Contributions by Plan Participants						0		0								20,000,000		34,000,000
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received						0		0								20,000,000		0
Defined Benefit Plan, Benefits Paid						(328,000,000)		(335,000,000)				(13,000,000)	(14,000,000)			(187,000,000)		(141,000,000)
Benefit obligations at end of year						4,492,000,000		4,171,000,000		4,005,000,000						1,866,000,000		2,000,000,000		1,162,000,000
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year					2,392,000,000	2,392,000,000		2,479,000,000								463,000,000		509,000,000
Actual return on plan assets						186,000,000		75,000,000								27,000,000		22,000,000
Defined Benefit Plan, Foreign Currency Exchange Rate Changes, Plan Assets						(9,000,000)		25,000,000										0
Defined Benefit Plan, Contributions by Employer						157,000,000		134,000,000								19,000,000		2,000,000
Defined Benefit Plan Change In Fair Value Of Plan Assets Benefits Paid						(315,000,000)		(321,000,000)								(72,000,000)		(70,000,000)
Fair value of plan assets at end of year						2,411,000,000		2,392,000,000		2,479,000,000						437,000,000		463,000,000		509,000,000
Funded status at year end						(2,081,000,000)		(1,779,000,000)								(1,429,000,000)		(1,537,000,000)
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities						14,000,000		13,000,000								92,000,000		93,000,000
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	3,405,000,000	3,210,000,000				2,067,000,000		1,766,000,000								1,337,000,000		1,444,000,000
Pension and Other Postretirement Defined Benefit Plans, Liabilities	3,511,000,000	3,316,000,000				2,081,000,000		1,779,000,000								1,429,000,000		1,537,000,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax						(2,529,000,000)		(2,170,000,000)								(558,000,000)		(654,000,000)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax						3,000,000		5,000,000								(13,000,000)		(21,000,000)
Net amount recognized						2,532,000,000		2,175,000,000								545,000,000		633,000,000
Defined Benefit Plan, Accumulated Benefit Obligation	4,400,000,000	4,100,000,000
Deferred Income Taxes and Other Assets, Noncurrent			772,000,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets [Abstract]
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation	4,492,000,000	4,171,000,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Accumulated Benefit Obligation	4,431,000,000	4,113,000,000
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets	2,411,000,000	2,392,000,000
Expected Future Pension Pan Contributions for Upcoming Year						166,000,000										2,000,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate				3.30%	4.20%	4.10%	[1]	4.80%	[1]	5.40%	[1]			5.60%	5.50%	4.20%	[1]	4.60%	[1]	5.60%	[1]
Defined benefit plan, benefits paid from Company assets																$ 75,000,000		$ 37,000,000

[1] In 2012 for pension benefits, the weighted average discount rate used to compute the expense for the period of November 1, 2011 through July 31, 2012 was 4.2%. Due to plan remeasurements at July 31, 2012 at a rate of 3.3%, the weighted average discount rate for the full fiscal year 2012 was 4.1%. In 2010 for health and life insurance benefits, the weighted average discount rate used to compute the expense for the period of November 1, 2009 through March 31, 2010 was 5.5%. Due to a plan remeasurement at March 31, 2010 at a rate of 5.6%, the weighted average discount rate for the full fiscal year 2010 was 5.6%.