Short-Term Financing (Details) (USD $)	3 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Jun. 30, 2011
Short-term Debt [Line Items]
Maturities of commercial paper range	overnight to up to 364 days
Issuance Of Debt [Member]
Short-term Debt [Line Items]
Aggregate amount of commercial paper issuable under the short-term commercial paper program	$ 6,750,000,000
Short-Term Commercial Paper Program [Member]
Short-term Debt [Line Items]
Average outstanding borrowings	3,000,000,000	2,200,000,000
Weighted average interest rate	0.10%	0.20%
Outstanding borrowings	0		0
Weighted average maturity of borrowings under the short-term commercial paper program	two days
364-Day Credit Agreement [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	2,000,000,000
Expiration date of credit facilities	June 2012
Credit Facility Expiring In June 2015 [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	3,250,000,000
Expiration date of credit facilities	June 2015
Line of credit facility potentially available increase in maximum borrowing capacity	500,000,000
Credit Facility Expiring In June 2013 [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	1,500,000,000
Expiration date of credit facilities	June 2013
Line of credit facility potentially available increase in maximum borrowing capacity	500,000,000
Reverse Repurchase Agreements [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	2,000,000,000
Average outstanding borrowings	496,800,000	608,900,000
Weighted average interest rate	0.50%	0.40%
Outstanding borrowings	$ 0		$ 0