Long-Term Debt (Revolving Credit Facility) (Details) (Line of Credit, USD $)	3 Months Ended
	Sep. 30, 2014
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 400,000,000
Long-term Line of Credit	0
Percentage of commitment on borrowing availability	0.25%
Letters of credit outstanding	32,399,000
Remaining borrowing capacity	367,601,000
Revolving Credit Facility, Covenant Terms
Covenant terms, distributions restrictions, borrowing availability threshold, percent of commitments, option 1	20.00%
Covenant terms, distributions restrictions, borrowing availability threshold, option 1	80,000,000
Covenant terms, distributions restrictions, borrowing availability threshold, percent of commitments, option 2	15.00%
Covenant terms, distributions restrictions, borrowing availability threshold, option 2	60,000,000
Covenant terms, distributions restrictions, fixed coverage ratio, option 2	100.00%
Covenant terms, acquisitions and investments, borrowing availability threshold, percent of commitments, option 1	15.00%
Covenant terms, acquisitions and investments, borrowing availability threshold, option 2	50,000,000
Covenant terms, acquisitions and investments, borrowing availability threshold, percent of commitments, option 2	12.50%
Covenant terms, acquisitions and investments restrictions, fixed coverage ration, option 2	100.00%
Covenant terms, specified investments permissible	50,000,000
Covenant terms, specified investments permissible, percentage of tangible assets and acquisitions	1.25%
Covenant terms, specified acquisitions permissible	100,000,000
Covenant terms, specified acquisitions permissible, percentage of tangible assets	2.50%
Covenant terms, acquisitions restrictions, borrowing availability threshold, percent of commitments, option 2	100.00%
Minimum
Line of Credit Facility [Line Items]
Increase in credit facility borrowings	25,000,000
Revolving Credit Facility, Covenant Terms
Covenant terms, acquisitions restrictions, borrowing availability threshold, percent of commitments, option 1	12.50%
Covenant terms, acquisitions restrictions, borrowing availability threshold, option 1	50,000,000
Maximum
Line of Credit Facility [Line Items]
Increase in credit facility borrowings	200,000,000
Revolving Credit Facility, Covenant Terms
Covenant terms, specified distributions permissible	75,000,000
Covenant terms, specified distributions permissible, annual increase, percentage	5.00%
Covenant terms, acquisitions restrictions, borrowing availability threshold, percent of commitments, option 1	15.00%
Covenant terms, acquisitions restrictions, borrowing availability threshold, option 1	60,000,000
LIBOR [Member]
Line of Credit Facility [Line Items]
Maximum basis spread, provided company is rated investment grade	1.50%
Revolving Credit Facility, Covenant Terms
Covenant terms, acquisitions and investments, borrowing availability threshold, option 1	$ 60,000,000
LIBOR [Member] | Minimum
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	1.25%
LIBOR [Member] | Maximum
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	1.75%
Base Rate [Member] | Minimum
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	0.00%
Base Rate [Member] | Maximum
Line of Credit Facility [Line Items]
Percentage added to basis to find interest rate	0.50%