Pension and Other Postretirement Benefits-Defined Benefit (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss transferred from 21CF, net of tax	$ 157
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Assets received from 21CF	630
Projected benefit obligations assumed from 21CF	765
Accumulated other comprehensive loss transferred from 21CF	188
Accumulated other comprehensive loss transferred from 21CF, net of tax	143
Accumulated benefit obligation		$ 1,319	$ 1,273
Projected benefit obligation	1,255	1,468	1,409
Fair value of plan asset	800	972	788
Pension Benefits | Overfunded Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation		96
Projected benefit obligation		96
Fair value of plan asset		100
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations assumed from 21CF	98
Accumulated other comprehensive loss transferred from 21CF	18
Accumulated other comprehensive loss transferred from 21CF, net of tax	14
Projected benefit obligation	103	98	104
Fair value of plan asset	$ 0	$ 0	$ 0