Financial Instruments Summary of Estimated Fair Value of Long-term Obligations and Other Short-term Borrowings (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jun. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount of Long-Term and other Short-Term Borrowings	$ 6,733	$ 6,775
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value	$ 7,414	$ 7,273