Postretirement Benefits - Defined Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014 Pension Plan, Defined Benefit [Member]	Apr. 30, 2013 Pension Plan, Defined Benefit [Member]	Apr. 30, 2014 Pension Plan, Defined Benefit [Member]	Apr. 30, 2013 Pension Plan, Defined Benefit [Member]	Oct. 31, 1993 Other Pension Plan, Postretirement or Supplemental Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amounts contributed to meet regulatory funding requirements					$ 36	$ 30	$ 65	$ 57
Defined Contribution Plan, Cost Recognized	7	8	15	15
Contribution to the Supplemental Trust shares									25.5
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			$ 133