Debt (Details) - USD ($)	9 Months Ended
	Mar. 31, 2018	Jun. 30, 2017
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 2,698,000
Debt Issuance Costs, Current, Net	551,000	$ 105,000
Debt Issuance Costs, Noncurrent, Net	1,936,000	294,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	250,000,000
Line of Credit Facility, Amount Outstanding	87,500,000
Letters of Credit Outstanding, Amount	3,637,000	2,441,000
Line of Credit Facility, Remaining Borrowing Capacity	$ 158,863,000	247,559,000
Debt, Weighted Average Interest Rate	3.49%
Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.10%
Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.20%
Long-term Debt [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount	$ 780,000,000
Long-term Debt	$ 780,000,000	$ 120,313,000
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	3.69%	2.25%
Prudential Facility [Domain]
Line of Credit Facility [Line Items]
Long-term Debt	$ 170,000,000
Debt Instrument, Unused Borrowing Capacity, Amount	50,000,000
Prudential Facility [Domain] | Minimum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Fee Amount	0.0025
Prudential Facility [Domain] | Maximum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Fee Amount	0.0125
Prudential Facility - Series C [Member]
Line of Credit Facility [Line Items]
Long-term Debt	$ 120,000,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	3.19%
Prudential Facility - Series D [Member]
Line of Credit Facility [Line Items]
Long-term Debt	$ 50,000,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	3.21%
State of Ohio Assumed Debt [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount	$ 2,359,000
Long-term Debt	$ 1,496,000	$ 1,669,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	1.50%