Pension and Other Postretirement Benefits (Schedule of Amounts Recognized in Balance Sheets) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Net amount recognized	$ (725)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accrued pension liabilities	(621)	$ (455)
Net amount recognized	(621)	(455)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Accrued pension liabilities	(104)	(103)
Net amount recognized	$ (104)	$ (103)