Pension and Other Postretirement Benefits (Schedule of Accumulated Benefit Obligation Exceeds Fair Value of Plan Assets) (Details) - Pension Benefits - USD ($) $ in Millions		Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation		$ 1,113	$ 311
Funded Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		976	82
Accumulated benefit obligation		842	82
Fair value of plan assets		800	70
Unfunded Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation		279	240
Accumulated benefit obligation		271	229
Fair value of plan assets	[1]	$ 0	$ 0

[1] The fair value of the assets in the Grantor Trust as of June 30, 2019 and 21CF Grantor Trust attributable to the Company as of June 30, 2018 was $249 million and $265 million, respectively