Borrowings (Schedule of Long-term Debt) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Apr. 30, 2011	Jul. 31, 2010
Senior notes	$ 16,000	15,000
Unaccreted discount	(74)	(73)
Hedge accounting adjustment	242	298
Total	16,168	15,225
Less: current portion		(3,037)
Total long-term debt	16,168	12,188
Floating-Rate Notes, Due 2014 [Member]
Senior notes	1,250
Effective rate	0.56%
Debt instrument maturity	2014	2014
5.25% Fixed-Rate Notes, Due 2011 [Member]
Senior notes		3,000
Effective rate		3.12%
Fixed interest rate	5.25%	5.25%
Debt instrument maturity	2011	2011
2.90% Fixed-Rate Notes, Due 2014 [Member]
Senior notes	500	500
Effective rate	3.11%	3.11%
Fixed interest rate	2.90%	2.90%
Debt instrument maturity	2014	2014
1.625% Fixed-Rate Notes, Due 2014 [Member]
Senior notes	2,000
Effective rate	0.64%
Fixed interest rate	1.625%	1.625%
Debt instrument maturity	2014	2014
5.50% Fixed-Rate Notes, Due 2016 [Member]
Senior notes	3,000	3,000
Effective rate	3.09%	3.18%
Fixed interest rate	5.50%	5.50%
Debt instrument maturity	2016	2016
3.15% Fixed-Rate Notes, Due 2017 [Member]
Senior notes	750
Effective rate	0.86%
Fixed interest rate	3.15%	3.15%
Debt instrument maturity	2017	2017
4.95% Fixed-Rate Notes, Due 2019 [Member]
Senior notes	2,000	2,000
Effective rate	5.08%	5.08%
Fixed interest rate	4.95%	4.95%
Debt instrument maturity	2019	2019
4.45% Fixed-Rate Notes, Due 2020 [Member]
Senior notes	2,500	2,500
Effective rate	4.50%	4.50%
Fixed interest rate	4.45%	4.45%
Debt instrument maturity	2020	2020
5.90% Fixed-Rate Notes, Due 2039 [Member]
Senior notes	2,000	2,000
Effective rate	6.11%	6.11%
Fixed interest rate	5.90%	5.90%
Debt instrument maturity	2039	2039
5.50% Fixed-Rate Notes, Due 2040 [Member]
Senior notes	$ 2,000	2,000
Effective rate	5.67%	5.67%
Fixed interest rate	5.50%	5.50%
Debt instrument maturity	2040	2040
Commercial Paper [Member]
Debt instrument maturity	May 2011