Pension and Other Postretirement Benefits (Schedule of Accumulated Benefit Obligation Exceeds Fair Value of Plan Assets) (Details) - Pension Benefits - USD ($) $ in Millions		Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation		$ 1,273	$ 1,113
Funded Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		1,096	976
Accumulated benefit obligation		971	842
Fair value of plan assets		788	800
Unfunded Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		313	279
Accumulated benefit obligation		302	271
Fair value of plan assets	[1]	$ 0	$ 0

[1] The fair value of the assets in the Grantor Trust as of June 30, 2020 and 2019 was $247 million and $249 million, respectively