Credit Arrangements (Details) $ in Millions	12 Months Ended
	Jun. 30, 2017 USD ($)
Letter Of Credit [Member]
Line of Credit Facility [Line Items]
Credit agreement capacity	$ 4.0
Line of Credit Facility, Amount Outstanding	1.3
Unsecured [Member]
Line of Credit Facility [Line Items]
Credit agreement capacity	$ 10.0
Interest rate under prime rate	2.00%
Line of Credit Facility, Amount Outstanding	$ 0.0
Line of Credit Facility, Interest Rate at Period End	2.25%
Line Of Credit [Member]
Line of Credit Facility [Line Items]
Credit agreement capacity	$ 10.0
Interest rate over LIBOR	1.00%
Line of Credit Facility, Amount Outstanding	$ 0.0
Line of Credit Facility, Remaining Borrowing Capacity	$ 8.7
Line of Credit Facility, Interest Rate at Period End	2.22%