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Pension and Other Postretirement Benefits (Health Care Cost Trend Rates) (Details) - Postretirement Benefits
12 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]    
Health care cost trend rate 6.00% 7.30%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.00% 4.50%
Year that the rate reaches the ultimate trend rate 2047 2039