Long-term Debt (Details) - USD ($)	3 Months Ended
	Sep. 30, 2017	Jun. 30, 2017
Debt Instrument [Line Items]
Total long-term debt	$ 707,500,000	$ 700,625,000
Unamortized debt issuance costs	(2,241,000)	(2,388,000)
Current portion of long-term debt	(62,500,000)	(62,500,000)
Long-term debt	$ 642,759,000	635,737,000
Subordinated note receivable, interest rate	4.25%
Line of Credit [Member] | Asset Backed Bank Facility [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 75,000,000	75,000,000
Line of credit facility, maximum borrowing capacity	100,000,000	100,000,000
Accounts receivable outstanding under the revolving agreement	174,000,000
Line of Credit [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt, gross	95,000,000	85,000,000
Line of credit facility, maximum borrowing capacity	200,000,000	200,000,000
Term Loan Facility [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Long-term debt, gross	237,500,000	240,625,000
Senior Notes [Member] | Senior Notes 3.04% due 2018 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 50,000,000	$ 50,000,000
Debt instrument, stated interest rate	3.04%	3.04%
Senior Notes [Member] | Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000,000	$ 100,000,000
Senior Notes [Member] | Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 150,000,000	$ 150,000,000