Borrowings (Schedule Of Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jan. 28, 2012	Jul. 30, 2011
Debt Instrument [Line Items]
Unaccreted discount	$ (71)	$ (73)
Hedge accounting adjustment	370	307
Long-term debt including current portion before unaccreted discount and hedge accounting adjustment	16,000	16,000
Total long-term debt	16,299	16,234
Floating-Rate Notes, Due 2014 [Member]
Debt Instrument [Line Items]
Senior notes	1,250	1,250
Effective rate	0.89%	0.60%
Debt instrument maturity	2014
1.625% Fixed-Rate Notes, Due 2014 [Member]
Debt Instrument [Line Items]
Senior notes	2,000	2,000
Effective rate	0.88%	0.58%
Fixed interest rate	1.625%
Debt instrument maturity	2014
2.90% Fixed-Rate Notes, Due 2014 [Member]
Debt Instrument [Line Items]
Senior notes	500	500
Effective rate	3.11%	3.11%
Fixed interest rate	2.90%
Debt instrument maturity	2014
5.50% Fixed-Rate Notes, Due 2016 [Member]
Debt Instrument [Line Items]
Senior notes	3,000	3,000
Effective rate	3.17%	3.06%
Fixed interest rate	5.50%
Debt instrument maturity	2016
3.15% Fixed-Rate Notes, Due 2017 [Member]
Debt Instrument [Line Items]
Senior notes	750	750
Effective rate	1.11%	0.81%
Fixed interest rate	3.15%
Debt instrument maturity	2017
4.95% Fixed-Rate Notes, Due 2019 [Member]
Debt Instrument [Line Items]
Senior notes	2,000	2,000
Effective rate	5.08%	5.08%
Fixed interest rate	4.95%
Debt instrument maturity	2019
4.45% Fixed-Rate Notes, Due 2020 [Member]
Debt Instrument [Line Items]
Senior notes	2,500	2,500
Effective rate	4.50%	4.50%
Fixed interest rate	4.45%
Debt instrument maturity	2020
5.90% Fixed-Rate Notes, Due 2039 [Member]
Debt Instrument [Line Items]
Senior notes	2,000	2,000
Effective rate	6.11%	6.11%
Fixed interest rate	5.90%
Debt instrument maturity	2039
5.50% Fixed-Rate Notes, Due 2040 [Member]
Debt Instrument [Line Items]
Senior notes	$ 2,000	$ 2,000
Effective rate	5.67%	5.67%
Fixed interest rate	5.50%
Debt instrument maturity	2040