Long-Term Debt (Details) - USD ($) $ in Thousands		12 Months Ended
	Oct. 21, 2019	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Debt Instrument
Debt, long-term and short-term, combined amount, total		$ 840,000	$ 865,000
Unamortized debt issuance expense		(6,900)	(8,200)
Long-term debt		833,100	856,800
Payments of Financing Costs				$ 1,500
Loss on extinguishment of debt, net		0	0	17,600
Estimated future interest payments on debt		295,500
Estimated future interest payments on debt, next 12 months		59,400
Term Loan
Debt Instrument
Proceeds from issuance of long-term debt	$ 700,000
Repayments of Debt				(519,800)
Loss on extinguishment of debt, net				(17,600)
Periodic payment of long-term debt principal					$ 8,750
Excess cash flow prepayment				81,400
Write-off of Unamortized Debt Premium				6,900
Write-off of Interest Rate Swap Loss, previously recorded in AOCI				6,100
Write off of Deferred Debt Issuance Cost				4,600
Letter of Credit
Debt Instrument
Maximum borrowing capacity on line of credit		20,000
Revolving Credit Facility
Debt Instrument
Debt, long-term and short-term, combined amount, total		0	25,000
Maximum borrowing capacity on line of credit		250,000
Proceeds from borrowing under line of credit		0	115,000	164,000
Repayments of lines of credit		(25,000)	(189,000)	(65,000)
Remaining borrowing capacity on line of credit		250,000	225,000
Letters of credit outstanding, amount			0
7.00% Senior Notes Maturing in March 2030
Debt Instrument
Debt, long-term and short-term, combined amount, total		$ 840,000	$ 840,000
Long-term Debt, Gross				840,000
Old Revolving Credit Facility
Debt Instrument
Maximum borrowing capacity on line of credit					200,000
Letter of Credit - Old Credit Agreement
Debt Instrument
Maximum borrowing capacity on line of credit					$ 20,000
Senior Notes [Member] | 7.00% Senior Notes Maturing in March 2030
Debt Instrument
Long-term Debt, Gross				840,000
Payments of debt issuance costs and deferred financing fees				$ (10,200)