Postretirement Benefits - Defined Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014 Pension Plan, Defined Benefit [Member]	Jan. 31, 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			$ 29	$ 27
Defined Contribution Plan, Cost Recognized	8	7
Contribution to the Supplemental Trust shares					25.5
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	$ 169