Pension and Other Postretirement Benefits - Schedule of Weighted-average Assumptions Used to Determine Net Periodic Benefit Cost (Details)	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Long-term rate of compensation increase	3.50%	3.49%	3.52%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.91%	4.50%	4.48%
Expected long-term rate of return on plan assets	6.88%	6.92%	6.92%
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.86%	4.50%	4.26%
Expected long-term rate of return on plan assets	6.25%	6.25%	6.25%