Pension and Other Postretirement Benefits (Pension Plans in Which Accumulated Benefit Obligation Exceeds Fair Value of Plan Assets) (Details) - Pension Benefits - USD ($) $ in Millions		Jun. 30, 2021	Jun. 30, 2020
Funded Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		$ 990	$ 1,096
Accumulated benefit obligation		854	971
Fair value of plan assets	[1]	811	788
Unfunded Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		318	313
Accumulated benefit obligation		309	302
Fair value of plan assets	[1]	$ 0	$ 0

[1] The fair value of the assets in the Grantor Trust as of June 30, 2021 and 2020 was $304 million and $247 million, respectively.