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Excess cash flow prepayment

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Write-off of Interest Rate Swap Loss, previously recorded in AOCI

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Write-off of Unamortized Debt Premium

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of the required periodic payments applied to principal.

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Amount, after accumulated amortization, of debt discount.

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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No definition available.

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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For a debtor, the aggregate gain (loss) recognized on the restructuring of payables arises from the difference between the book value of the debt before the restructuring and the fair value of the payments on the debt after restructuring is complete.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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No definition available.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

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Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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Amount of cash outflow for payment of an obligation from a lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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No definition available.

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Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

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Long-Term Debt (Details) - USD ($)	3 Months Ended		9 Months Ended
Long-Term Debt (Details) - USD ($)	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Mar. 10, 2022	Sep. 30, 2021	Oct. 21, 2019
Debt Instrument
Long-term and short-term debt, combined amount	$ 924,000,000.0		$ 924,000,000.0			$ 609,900,000
Long-term Debt, Current Maturities	0		0			(116,300,000)
Unamortized Debt Issuance Expense	(9,800,000)		(9,800,000)			(4,700,000)
Debt Instrument, Unamortized Discount	0		0			(7,700,000)
Long-term debt	914,200,000		914,200,000			481,200,000
Payments of debt issuance costs and deferred financing fees			11,900,000	$ 1,600,000
Deferred financing fees			1,500,000
Loss on extinguishment and refinancing of debt, net	0	$ 100,000	17,600,000	1,600,000
7.00% Senior Notes Maturing in March 2030
Debt Instrument
Long-term debt, gross	840,000,000.0		840,000,000.0			0
Revolving Credit Facility
Debt Instrument
Long-term debt, gross	84,000,000.0		84,000,000.0			0
Maximum borrowing capacity on line of credit					$ 250,000,000.0
Proceeds from borrowing under line of credit			109,000,000.0
Remaining borrowing capacity on line of credit	166,000,000.0		166,000,000.0
Letters of credit outstanding, amount						0
Repayments of lines of credit			25,000,000.0
Letter of Credit
Debt Instrument
Maximum borrowing capacity on line of credit					$ 20,000,000.0
Old Revolving Credit Facility [Domain]
Debt Instrument
Maximum borrowing capacity on line of credit						200,000,000.0
Proceeds from borrowing under line of credit				20,000,000.0
Remaining borrowing capacity on line of credit						200,000,000.0
Letters of credit outstanding, amount						0
Repayments of lines of credit				50,000,000.0
Term Loan
Debt Instrument
Long-term debt, gross	0		0			609,900,000	$ 700,000,000.0
Periodic payment of long-term debt principal			8,750,000
Excess cash flow prepayment			(81,400,000)	$ (28,800,000)
Repayments of Debt			519,800,000
Loss on extinguishment and refinancing of debt, net			17,600,000
Write-off of Unamortized Debt Premium			6,900,000
Write-off of Interest Rate Swap Loss in AOCI			6,100,000
Write off of Deferred Debt Issuance Cost			4,600,000
Letter of Credit - Old Credit Agreement
Debt Instrument
Maximum borrowing capacity on line of credit						$ 20,000,000.0
Senior Notes [Member] \| 7.00% Senior Notes Maturing in March 2030
Debt Instrument
Long-term debt, gross	$ 840,000,000.0		840,000,000.0
Payments of debt issuance costs and deferred financing fees			$ 10,200,000