Pension and Other Postretirement Benefits (Funded and Unfunded Pension Plans) (Details) - Pension Benefits - USD ($) $ in Millions		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		$ 1,468	$ 1,409	$ 1,255
Accumulated benefit obligation		1,319	1,273
Fair value of plan assets		972	788	$ 800
Funded Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		1,150	1,096
Accumulated benefit obligation		1,010	971
Fair value of plan assets		972	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.