Short-Term Financing (Details) - USD ($)	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Short-term Debt [Line Items]
Outstanding borrowings	$ 0	$ 0
Commercial Paper	$ 0	0
Maturities of short-term funding agreements	overnight to up to five business days
Obligations under reverse repurchase agreements	$ 0	$ 0
364-Day Credit Agreement [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	$ 3,500,000,000
Term of credit	364 days
Expiration date of credit facilities	Jun. 16, 2018
Debt Instrument, Extension Option Term	1 year
Short-Term Commercial Paper Program [Member]
Short-term Debt [Line Items]
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]
Short-term Debt, Average Outstanding Amount	$ 274,800,000	$ 341,000,000
Debt Instrument, Interest Rate During Period	0.60%	0.40%
Credit Facility Expiring In June Two Thousand Twenty Two [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	$ 2,250,000,000
Term of credit	5 years
Expiration date of credit facilities	Jun. 17, 2022
Line of credit facility potentially available increase in maximum borrowing capacity	$ 500,000,000
Credit Facility Expiring In June Two Thousand Twenty One [Member]
Short-term Debt [Line Items]
Maximum borrowing capacity under credit facilities	$ 3,750,000,000
Term of credit	5 years
Expiration date of credit facilities	Jun. 18, 2021
Line of credit facility potentially available increase in maximum borrowing capacity	$ 500,000,000
Commercial Paper [Member]
Short-term Debt [Line Items]
Debt Instrument, Description	9250
Aggregate amount of commercial paper issuable under the short-term commercial paper program	$ 9,500,000,000
Maturities of commercial paper range	overnight to up to 364 days
Short-term Debt, Average Outstanding Amount	$ 3,100,000,000	$ 2,700,000,000
Debt Instrument, Interest Rate During Period	0.60%	0.30%