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Financial Instruments (Tables) | 12 Months Ended
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Sep. 30, 2025
Financial Instruments, Owned, at Fair Value, by Type, Alternative [Abstract] |
Schedule of Long-Term Debt | Based on these criteria, the fair market value of long-term debt, including current portion, was as follows:
| At September 30
| 2025 Carrying Amount |  | 2025 Fair Value |  | 2024 Carrying Amount |  | 2024 Fair Value
| (Thousands)
Long-Term Debt | $ | 2,682,861 |  |  | $ | 2,696,145 |  |  | $ | 2,688,243 |  |  | $ | 2,656,888 |
Schedule of Other Investments | The components of the Company’s Other Investments are as follows (in thousands):
| At September 30
| 2025 |  | 2024
| (Thousands)
Life Insurance Contracts | $ | 44,478 |  |  | $ | 44,808 |
Equity Mutual Fund | 13,786 |  |  | 19,523 |
Fixed Income Mutual Fund | 10,082 |  |  | 17,374 |
| $ | 68,346 |  |  | $ | 81,705 |
Schedule of Derivative Financial Instruments Designated and Qualifying as Cash Flow Hedges on the Statements of Financial Performance |
The Effect of Derivative Financial Instruments on the Statement of Financial Performance for the Year Ended September 30, 2025 and 2024 (Dollar Amounts in Thousands)
Derivatives in Cash Flow Hedging Relationships |  | Amount of Derivative Gain or (Loss) Recognized in Other Comprehensive Income (Loss) on the Consolidated Statement of Comprehensive Income (Loss) for the Year Ended September 30, |  | Location of Derivative Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) on the Consolidated Balance Sheet into the Consolidated Statement of Income |  | Amount of Derivative Gain or (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) on the Consolidated Balance Sheet into the Consolidated Statement of Income for the Year Ended September 30,
|  | 2025 |  | 2024 |  |  |  | 2025 |  | 2024
Commodity Contracts |  | $ | (1,795) |  |  | $ | 286,392 |  |  | Operating Revenue |  | $ | 46,957 |  |  | $ | 217,012 |
Foreign Currency Contracts |  | (1,371) |  |  | 502 |  |  | Operating Revenue |  | (1,066) |  |  | (357) |
Total |  | $ | (3,166) |  |  | $ | 286,894 |  |  |  |  | $ | 45,891 |  |  | $ | 216,655 |

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- Definition Tabular disclosure of investment. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org/320/tableOfContent Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Topic 321 -Publisher FASB -URI https://asc.fasb.org/321/tableOfContent Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Topic 325 -Publisher FASB -URI https://asc.fasb.org/325/tableOfContent + Details
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- Definition Tabular disclosure of derivative instruments (including nonderivative instruments that are designated and qualify as hedging instruments) of (a) the location and amount of gains and losses reported in the statement of financial performance and (b) the location and fair value amounts of the instruments reported in the statement of financial position. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4E Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C + Details
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