Financial Instruments (Summary of Estimated Fair Value of Long-term Obligations and Other Short-term Borrowings) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jun. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying amount	$ 8,031	$ 9,013
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value	8,065	$ 8,852
Interest Rate Swaps | Designated as Hedging Instrument | Fair Value Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, Hedge Discontinuances, Termination of Hedging Instrument, Amount	$ 163