Fair Value Measurements (Notional Amounts And Fair Values Of Interest Rate Swaps) (Details) (USD $) In Millions, unless otherwise specified	Oct. 31, 2011	Jan. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	$ 9,429	$ 9,779
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	528	720
Fair Value Hedges [Member] | Fixed-Rate Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	3,945	4,445
Fair Value Hedges [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	213	267
Net Investment Hedges [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 Hedges [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	291	233
Cash Flow Hedges [Member] | Cross-Currency Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	2,994	2,902
Cash Flow Hedges [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	41	238
Cash Flow Hedges [Member] | Floating-Rate Interest Rate Swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional Amount	1,240	1,182
Cash Flow Hedges [Member] | Floating-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	$ (17)	$ (18)