Derivative Financial Instruments (Balance Sheet Classification Of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Oct. 31, 2014	Jan. 31, 2014
Fair Value Hedging [Member]
Derivative [Line Items]
Derivative Assets		$ 5
Fair Value Hedging [Member] | PrepaidExpensesandandOther [Member]
Derivative [Line Items]
Derivative Assets		5
Net Investment Hedging [Member]
Derivative [Line Items]
Derivative Assets	138	97
Nonderivative Hedging Instruments	4,916	6,068
Net Investment Hedging [Member] | OtherAssetsandDeferredCharges [Member]
Derivative [Line Items]
Derivative Assets	138	97
Net Investment Hedging [Member] | LongTermDebtDueWithinOneYear(HedgedItem) [Member]
Derivative [Line Items]
Nonderivative Hedging Instruments	824	973
Net Investment Hedging [Member] | Long-term Debt [Member]
Derivative [Line Items]
Nonderivative Hedging Instruments	4,092	5,095
Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative Assets	362	619
Derivative Liabilities	148	2
Cash Flow Hedging [Member] | OtherAssetsandDeferredCharges [Member]
Derivative [Line Items]
Derivative Assets	362	619
Cash Flow Hedging [Member] | Accrued Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities	1	1
Cash Flow Hedging [Member] | DeferredIncomeTaxesandOther [Member]
Derivative [Line Items]
Derivative Liabilities	$ 147	$ 1