Short-Term Financing (Details) (USD $)	3 Months Ended		9 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011	Jun. 30, 2011
Short-term Debt [Line Items]
Maturities of commercial paper range			overnight to up to 364 days
Maturities of short-term funding agreements			overnight to up to five business days
Short-Term Commercial Paper Program [Member]
Short-term Debt [Line Items]
Average outstanding borrowings	$ 500,000,000	$ 600,000,000	$ 2,300,000,000	$ 1,700,000,000
Weighted average interest rates	0.10%	0.20%	0.10%	0.20%
Outstanding borrowings	0		0		0
Weighted average maturity of borrowings under the short-term commercial paper program	1 day		2 days
364-Day Credit Agreement [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	2,000,000,000		2,000,000,000
Expiration date of credit facilities			Jun. 01, 2012
Outstanding borrowings	0		0
Credit Facility Expiring In June 2015 [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	3,250,000,000		3,250,000,000
Expiration date of credit facilities			Jun. 01, 2015
Line of credit facility potentially available increase in maximum borrowing capacity			500,000,000
Term of credit			4 years
Credit Facility Expiring In June 2013 [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	1,500,000,000		1,500,000,000
Expiration date of credit facilities			Jun. 01, 2013
Line of credit facility potentially available increase in maximum borrowing capacity			500,000,000
Term of credit			3 years
Reverse Repurchase Agreements [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	2,000,000,000		2,000,000,000
Average outstanding borrowings	139,900,000	160,300,000	303,300,000	439,000,000
Weighted average interest rates	1.00%	0.80%	0.60%	0.50%
Outstanding borrowings	0		0		0
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