Short-Term Financing (Details) (USD $)	3 Months Ended	12 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012
Short-term Debt [Line Items]
Obligations under reverse repurchase agreements	$ 245,900,000	$ 245,900,000	$ 0
Credit agreement period		364 days
Aggregate amount of commercial paper issuable under the short-term commercial paper program		6,750,000,000
Maturities of commercial paper range		overnight to up to 364 days
Maturities of short-term funding agreements		overnight to up to five business 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, 2014
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
Term of credit		4 years
Expiration date of credit facilities		Jun. 01, 2015
Line of credit facility potentially available increase in maximum borrowing capacity		500,000,000
Credit Facility Expiring In June 2018 [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	2,000,000,000	2,000,000,000
Term of credit		5 years
Expiration date of credit facilities		Jun. 01, 2018
Credit Facility Expiring In June 2017 [Member]
Short-term Debt [Line Items]
Line of credit facility potentially available increase in maximum borrowing capacity		500,000,000
Short-Term Commercial Paper Program [Member]
Short-term Debt [Line Items]
Outstanding borrowings	0	0	0
Average outstanding borrowings		2,400,000,000	2,300,000,000
Weighted average interest rates		0.20%	0.10%
Weighted average maturity of borrowings under the short-term commercial paper program		2 days	2 days
Reverse Repurchase Agreements [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	3,000,000,000	3,000,000,000
Outstanding borrowings			0
Debt Instrument, Maturity Date	Jul. 02, 2013
Average outstanding borrowings		362,000,000	297,700,000
Weighted average interest rates		0.70%	0.60%
Issuance Of Debt [Member]
Short-term Debt [Line Items]
Aggregate amount of commercial paper issuable under the short-term commercial paper program		$ 7,250,000,000
Debt Instrument, Issuance Date		Aug. 01, 2013