Postretirement Benefits Assumptions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended	1 Months Ended			3 Months Ended	12 Months Ended				1 Months Ended			5 Months Ended	12 Months Ended
	Oct. 31, 2011	Oct. 31, 2011 Pension [Member]		Jan. 31, 2009 Pension [Member]	Jan. 31, 2009 Pension [Member]	Oct. 31, 2010 Pension [Member]		Oct. 31, 2009 Pension [Member]		Oct. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit [Member]		Mar. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]	Mar. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]	Oct. 31, 2010 Other Postretirement Benefit Plans, Defined Benefit [Member]		Oct. 31, 2009 Other Postretirement Benefit Plans, Defined Benefit [Member]		Oct. 31, 2009 Effect Of Remeasurement On Plan [Member] Pension [Member]
Weighted Average Assumptions Used in Determining Benefit Obligation [Abstract]
Discount rate used to determine present value of benefit obligation at end of year		4.20%				4.80%				4.20%				4.60%
Expected rate of increase in future compensation levels		3.50%				3.50%				0.00%				0.00%
Weighted Average Assumptions Used in Determining Net Postretirement Benefits Expense [Abstract]
Discount rate		4.80%	[1]	6.50%	8.30%	5.40%	[1]	7.60%	[1]	4.60%	[1]	5.60%	5.50%	5.60%	[1]	8.40%	[1]	7.60%
Expected long-term rate of return on plan assets		8.50%				8.50%		9.00%		8.50%				8.50%		9.00%
Expected rate of increase in future compensation levels		3.50%				3.50%		3.50%		0.00%				0.00%		0.00%
Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect of One Percentage Point Increase on Service and Interest Cost Components	$ 5
Effect of One Percentage Point Decrease on Service and Interest Cost Components	(8)
Effect of One Percentage Point Increase on Postretirement Benefit Obligation	192
Effect of One Percentage Point Decrease on Postretirement Benefit Obligation	$ (201)

[1] In 2009 for pension benefits, the weighted average discount rate used to compute the expense for the period of November 1, 2008 through January 31, 2009 was 8.3%. Due to a plan remeasurement at January 31, 2009 at a rate of 6.5%, the weighted average discount rate for the full fiscal year 2009 was 7.6%. 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%.