Financial Instruments (Summary of Estimated Fair Value of Long-term Obligations and Other Short-term Borrowings) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount of Long-Term and other Short-Term Borrowings	$ 5,654	$ 6,236
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value	$ 6,132	$ 6,751