Derivative Financial Instruments (Balance Sheet Classification Of Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 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	82	97
Derivative Liabilities	4
Nonderivative Hedging Instruments	6,155	6,068
Net Investment Hedging [Member] | OtherAssetsandDeferredCharges [Member]
Derivative [Line Items]
Derivative Assets	82	97
Net Investment Hedging [Member] | DeferredIncomeTaxesandOther [Member]
Derivative [Line Items]
Derivative Liabilities	4
Net Investment Hedging [Member] | LongTermDebtDueWithinOneYear(HedgedItem) [Member]
Derivative [Line Items]
Nonderivative Hedging Instruments	974	973
Net Investment Hedging [Member] | Long-term Debt [Member]
Derivative [Line Items]
Nonderivative Hedging Instruments	5,181	5,095
Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative Assets	535	619
Derivative Liabilities	17	2
Cash Flow Hedging [Member] | OtherAssetsandDeferredCharges [Member]
Derivative [Line Items]
Derivative Assets	535	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	$ 16	$ 1