Financial Instruments (Summary of estimated fair value of our long-term obligations and other short-term borrowings) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Jun. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying amount	$ 5,550	$ 5,492
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated fair value	$ 5,618	$ 5,521