Financial Instruments (Summary of Estimated Fair Value of Long-term Obligations and Other Short-term Borrowings) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Jun. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying amount	$ 5,462	$ 5,539
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value	$ 5,611	$ 5,780