Credit Arrangements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Mar. 31, 2015	Mar. 31, 2015	Jan. 11, 2015	Dec. 31, 2014
Credit agreement capacity	$ 65.0	$ 65.0	$ 25.0
Interest rate over LIBOR		(1.18%)
Interest rate under prime rate		(1.25%)
Line of Credit Facility, Amount Outstanding	14.7	14.7
Assets Held-in-trust	3.5	3.5
Funded Debt to EBITDA covenant	2.5
Letters Of Credit [Member]
Credit agreement capacity	4.0	4.0
Line of Credit Facility, Amount Outstanding	2.9	2.9
Line of Credit Facility, Remaining Borrowing Capacity	47.4	47.4
Unsecured [Member]
Credit agreement capacity	$ 10.0	$ 10.0		$ 8.0