Debt (Details) - USD ($) $ in Thousands	6 Months Ended
	Dec. 31, 2017	Jun. 30, 2017
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 2,698
Debt Issuance Costs, Current, Net	105
Debt Issuance Costs, Noncurrent, Net	242	$ 294
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	250,000
Line of Credit Facility, Amount Outstanding	23,000
Letters of Credit Outstanding, Amount	2,459	2,441
Line of Credit Facility, Remaining Borrowing Capacity	$ 224,541	247,559
Debt, Weighted Average Interest Rate	3.60%
Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.09%
Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.175%
Long-term Debt [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount	$ 125,000
Long-term Debt	$ 118,750	$ 120,313
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	2.63%	2.25%
Prudential Facility [Domain]
Line of Credit Facility [Line Items]
Long-term Debt	$ 170,000
Debt Instrument, Unused Borrowing Capacity, Amount	50,000
Prudential Facility - Series C [Member]
Line of Credit Facility [Line Items]
Long-term Debt	$ 120,000
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
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
Long-term Debt	$ 1,554	$ 1,669
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	1.50%