Pension and Other Postretirement Benefits - Schedule of Weighted-average Assumptions Used to Determine Net Periodic Benefit Cost (Details)	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.61%	4.32%	3.92%
Expected long-term rate of return on plan assets	6.68%	6.88%	6.87%
Long-term rate of compensation increase	3.31%	3.39%	3.44%
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.60%	4.32%	3.89%
Expected long-term rate of return on plan assets	6.25%	6.25%	6.25%