Cash equivalents, maturity period.

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Derivative maximum payout under weather hedge contract.

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Right to receive payment under weather hedge contract.

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Schedule Of Significant Accounting Policies [Line Items]

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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Amount of assets held-for-sale that are not part of a disposal group.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; including, but not limited to, disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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- Definition

Fair value of all asset derivatives designated as cash flow hedging instruments.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Amount of the obligation recognized by withdrawing from a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

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Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.

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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Schedule Of Significant Accounting Policies [Line Items]
Cash, cash equivalents, and restricted cash	$ 22,841,000	$ 21,489,000		$ 14,870,000	$ 5,017,000
Cash and cash equivalents	22,591,000			14,620,000
Restricted cash	250,000			250,000	$ 300,000
Accrued expenses and other current liabilities	120,152,000			125,561,000
Other long-term liabilities	14,780,000			14,766,000
Interest Rate Swap Agreements \| Cash Flow Hedging Derivatives
Schedule Of Significant Accounting Policies [Line Items]
Cash flow hedging derivatives, amount	52,800,000
Propane Assets \| Goodwill
Schedule Of Significant Accounting Policies [Line Items]
Assets held-for-sale				2,200,000
Propane Assets \| Property and Equipment, Net
Schedule Of Significant Accounting Policies [Line Items]
Assets held-for-sale				800,000
New England Teamsters & Trucking Industry Pension Fund
Schedule Of Significant Accounting Policies [Line Items]
Accrued expenses and other current liabilities	300,000			300,000
Other long-term liabilities	16,200,000			16,200,000
New England Teamsters & Trucking Industry Pension Fund \| Significant Other Observable Inputs Level 2
Schedule Of Significant Accounting Policies [Line Items]
Multiemployer plan discounted withdrawal liability	20,000,000.0			$ 20,200,000
Financial Products Corporation
Schedule Of Significant Accounting Policies [Line Items]
Delivery and branch expense increased (reduced) under weather hedge contract	$ 400,000	$ (2,200,000)
Scenario Forecast
Schedule Of Significant Accounting Policies [Line Items]
Derivative maximum payout			$ 5,000,000.0
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Cash equivalents, highly liquid investments maturity	3 months
Maximum \| Scenario Forecast
Schedule Of Significant Accounting Policies [Line Items]
Derivative maximum receivable			$ 12,500,000