Fair Value Measurements (Notional Amounts And Fair Values Of Interest Rate Swaps) (Details) (Recurring [Member], USD $) In Millions, unless otherwise specified	Oct. 31, 2012	Jan. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	$ 13,819	$ 9,349
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	123	480
Fair Value Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	3,445	3,945
Fair Value Hedging [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	92	183
Net Investment Hedging [Member] | Cross-Currency Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	1,250	1,250
Net Investment Hedging [Member] | Cross-Currency Interest Rate Swaps [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	234	316
Cash Flow Hedging [Member] | Cross-Currency Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	2,909	2,884
Cash Flow Hedging [Member] | Cross-Currency Interest Rate Swaps [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	34	(3)
Cash Flow Hedging [Member] | Fixed-Rate Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	1,215	1,270
Cash Flow Hedging [Member] | Fixed-Rate Interest Rate Swaps [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	(11)	(16)
Cash Flow Hedging [Member] | Forward Starting Interest Rate Swap [Domain]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	5,000	0
Cash Flow Hedging [Member] | Forward Starting Interest Rate Swap [Domain] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ (226)	$ 0