Long-term Debt (Schedule of Long-term Debt and Maturities of Long-term Debt) (Details) - USD ($)	Jun. 30, 2017	Jun. 30, 2016
Debt Instrument [Line Items]
Debt Issuance Costs, Net	$ 2,388,000	$ 1,494,000
Long-term Debt [Abstract]
Total long-term debt	700,625,000	695,000,000
Current portion of long-term debt	(62,500,000)	(75,000,000)
Long-term debt	635,737,000	618,506,000
Principal payments on debt due in succeeding fiscal years [Abstract]
2018	62,500,000
2019	21,875,000
2020	25,000,000
2021	25,000,000
2022	316,250,000
Thereafter	250,000,000
Variable-rate credit facilities [Member] | Asset-backed Bank Facility [Member]
Long-term Debt [Abstract]
Maximum borrowing capacity	100,000,000
Total long-term debt	75,000,000	80,000,000
Variable-rate credit facilities [Member] | Revolving Credit Facility [Member]
Long-term Debt [Abstract]
Maximum borrowing capacity	200,000,000
Term loan facility [Member] | Term Loan Facility [Member]
Long-term Debt [Abstract]
Maximum borrowing capacity	250,000,000
Total long-term debt	240,625,000	$ 225,000,000
Private placement notes [Member] | Senior Notes Due 2017 [Member]
Long-term Debt [Abstract]
Stated interest rate		3.04%
Total long-term debt	$ 0	$ 50,000,000
Private placement notes [Member] | Senior Notes Due 2018 [Member]
Long-term Debt [Abstract]
Stated interest rate	3.04%
Total long-term debt	$ 50,000,000	50,000,000
Private placement notes [Member] | Senior Notes Due 2022 [Member]
Long-term Debt [Abstract]
Total long-term debt	100,000,000	100,000,000
Private placement notes [Member] | Senior Notes Due 2024 [Member]
Long-term Debt [Abstract]
Total long-term debt	150,000,000	150,000,000
Revolving Credit Facility [Member] | Variable-rate credit facilities [Member]
Long-term Debt [Abstract]
Total long-term debt	$ 85,000,000	$ 40,000,000