v3.25.2
Fair Value Measurements - Recurring Fair Value Measures Of Assets And Liabilities (Details) - USD ($)
$ in Thousands
Jun. 30, 2025
Sep. 30, 2024
Assets:    
Cash Equivalents – Money Market Mutual Funds [1] $ 26,831 $ 29,238
Cash Equivalents - Money Market Mutual Funds Netting Adjustments 0 0
Derivative Financial Instruments:    
Derivative Asset Netting Adjustment [1] $ (44,674) $ (21,698)
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Fair Value of Derivative Financial Instruments Fair Value of Derivative Financial Instruments
Total Assets [1] $ 59,216 $ 154,040
Derivative Financial Instruments:    
Derivative Liability Netting Adjustments [1] $ (44,674) $ (21,698)
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Fair Value of Derivative Financial Instruments Fair Value of Derivative Financial Instruments
Total Liabilities [1] $ 57,228 $ 4,735
Total Net Assets/(Liabilities) Netting Adjustments [1] 0 0
Total Net Assets/(Liabilities) [1] 1,988 149,305
Over the Counter Swaps – Gas    
Derivative Financial Instruments:    
Derivative Asset Netting Adjustment [1] (32,440) (17,198)
Derivative asset [1] 2,005 58,811
Derivative Financial Instruments:    
Derivative Liability Netting Adjustments [1] (32,440) (17,198)
Derivative liability [1] 30,457 5,008
Over the Counter No Cost Collars – Gas    
Derivative Financial Instruments:    
Derivative Asset Netting Adjustment [1] (11,750) (3,774)
Derivative asset [1] 548 28,810
Derivative Financial Instruments:    
Derivative Liability Netting Adjustments [1] (11,750) (3,774)
Derivative liability [1] 26,763 (273)
Contingent Consideration for Asset Sale    
Derivative Financial Instruments:    
Derivative Asset Netting Adjustment [1] 0 0
Derivative asset [1] 0 729
Foreign Currency Contracts    
Derivative Financial Instruments:    
Derivative Asset Netting Adjustment [1] (484) (726)
Derivative asset [1] (159) (445)
Derivative Financial Instruments:    
Derivative Liability Netting Adjustments [1] (484) (726)
Derivative liability [1] 8 0
Balanced Equity Mutual Fund    
Derivative Financial Instruments:    
Other Investments [1] 13,143 19,523
Derivative Financial Instruments:    
Other Investments Netting Adjustments [1] 0 0
Fixed Income Mutual Fund    
Derivative Financial Instruments:    
Other Investments [1] 16,848 17,374
Derivative Financial Instruments:    
Other Investments Netting Adjustments [1] 0 0
Level 1    
Assets:    
Cash Equivalents – Money Market Mutual Funds 26,831 29,238
Derivative Financial Instruments:    
Total Assets 56,822 66,135
Derivative Financial Instruments:    
Total Liabilities 0 0
Total Net Assets/(Liabilities) 56,822 66,135
Level 1 | Over the Counter Swaps – Gas    
Derivative Financial Instruments:    
Derivative Asset 0 0
Derivative Financial Instruments:    
Derivative Liability 0 0
Level 1 | Over the Counter No Cost Collars – Gas    
Derivative Financial Instruments:    
Derivative Asset 0 0
Derivative Financial Instruments:    
Derivative Liability 0 0
Level 1 | Contingent Consideration for Asset Sale    
Derivative Financial Instruments:    
Derivative Asset 0 0
Level 1 | Foreign Currency Contracts    
Derivative Financial Instruments:    
Derivative Asset 0 0
Derivative Financial Instruments:    
Derivative Liability 0 0
Level 1 | Balanced Equity Mutual Fund    
Derivative Financial Instruments:    
Other Investments 13,143 19,523
Level 1 | Fixed Income Mutual Fund    
Derivative Financial Instruments:    
Other Investments 16,848 17,374
Level 2    
Assets:    
Cash Equivalents – Money Market Mutual Funds 0 0
Derivative Financial Instruments:    
Total Assets 47,068 109,603
Derivative Financial Instruments:    
Total Liabilities 101,902 26,433
Total Net Assets/(Liabilities) (54,834) 83,170
Level 2 | Over the Counter Swaps – Gas    
Derivative Financial Instruments:    
Derivative Asset 34,445 76,009
Derivative Financial Instruments:    
Derivative Liability 62,897 22,206
Level 2 | Over the Counter No Cost Collars – Gas    
Derivative Financial Instruments:    
Derivative Asset 12,298 32,584
Derivative Financial Instruments:    
Derivative Liability 38,513 3,501
Level 2 | Contingent Consideration for Asset Sale    
Derivative Financial Instruments:    
Derivative Asset 0 729
Level 2 | Foreign Currency Contracts    
Derivative Financial Instruments:    
Derivative Asset 325 281
Derivative Financial Instruments:    
Derivative Liability 492 726
Level 2 | Balanced Equity Mutual Fund    
Derivative Financial Instruments:    
Other Investments 0 0
Level 2 | Fixed Income Mutual Fund    
Derivative Financial Instruments:    
Other Investments 0 0
Level 3    
Assets:    
Cash Equivalents – Money Market Mutual Funds 0 0
Derivative Financial Instruments:    
Total Assets 0 0
Derivative Financial Instruments:    
Total Liabilities 0 0
Total Net Assets/(Liabilities) 0 0
Level 3 | Over the Counter Swaps – Gas    
Derivative Financial Instruments:    
Derivative Asset 0 0
Derivative Financial Instruments:    
Derivative Liability 0 0
Level 3 | Over the Counter No Cost Collars – Gas    
Derivative Financial Instruments:    
Derivative Asset 0 0
Derivative Financial Instruments:    
Derivative Liability 0 0
Level 3 | Contingent Consideration for Asset Sale    
Derivative Financial Instruments:    
Derivative Asset 0 0
Level 3 | Foreign Currency Contracts    
Derivative Financial Instruments:    
Derivative Asset 0 0
Derivative Financial Instruments:    
Derivative Liability 0 0
Level 3 | Balanced Equity Mutual Fund    
Derivative Financial Instruments:    
Other Investments 0 0
Level 3 | Fixed Income Mutual Fund    
Derivative Financial Instruments:    
Other Investments $ 0 $ 0
[1] Netting Adjustments represent the impact of legally-enforceable master netting arrangements that allow the Company to net gain and loss positions held with the same counterparties. The net asset or net liability for each counterparty is recorded as an asset or liability on the Company’s balance sheet.