Short-term Borrowings and Long-term Debt Schedule of Long-Term Debt (Details) (USD $) In Millions, unless otherwise specified	Jan. 31, 2015	Jan. 31, 2014
Debt Instrument [Line Items]
Long-term Debt	$ 45,896us-gaap_LongTermDebt	$ 45,874us-gaap_LongTermDebt
Long-term Debt, Current Maturities	(4,810)us-gaap_LongTermDebtCurrent	(4,103)us-gaap_LongTermDebtCurrent
Long-term debt	41,086us-gaap_LongTermDebtNoncurrent	41,771us-gaap_LongTermDebtNoncurrent
Fixed
Debt Instrument [Line Items]
Long-term Debt	36,000	35,500
Debt Weighted Average Interest Rate Fixed	4.30%	4.30%
Variable
Debt Instrument [Line Items]
Long-term Debt	500	500
Debt Weighted Average Interest Rate Variable	5.40%	5.40%
Total U.S. dollar denominated
Debt Instrument [Line Items]
Long-term Debt	36,500	36,000
Fixed
Debt Instrument [Line Items]
Long-term Debt	2,821	1,356
Debt Weighted Average Interest Rate Fixed	3.30%	4.90%
Variable
Debt Instrument [Line Items]
Long-term Debt	0	0
Total Euro denominated
Debt Instrument [Line Items]
Long-term Debt	2,821	1,356
Fixed
Debt Instrument [Line Items]
Long-term Debt	5,271	5,770
Debt Weighted Average Interest Rate Fixed	5.30%	5.30%
Variable
Debt Instrument [Line Items]
Long-term Debt	0	0
Total Sterling denominated
Debt Instrument [Line Items]
Long-term Debt	5,271	5,770
Fixed
Debt Instrument [Line Items]
Long-term Debt	596	1,490
Debt Weighted Average Interest Rate Fixed	1.00%	1.30%
Variable
Debt Instrument [Line Items]
Long-term Debt	255	457
Debt Weighted Average Interest Rate Variable	0.60%	0.70%
Total Yen denominated
Debt Instrument [Line Items]
Long-term Debt	851	1,947
Total unsecured debt
Debt Instrument [Line Items]
Long-term Debt	45,443	45,073
Total other debt (in USD)(2)
Debt Instrument [Line Items]
Long-term Debt	$ 453	$ 801

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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