Pension and Other Postretirement Benefits (Schedule of Amounts Recognized in Balance Sheets) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	$ (558)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accrued pension liabilities	(455)	$ (252)
Net amount recognized	(455)	(252)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Accrued pension liabilities	(103)	0
Net amount recognized	$ (103)	$ 0