Fair Value Measurements (Recurring Fair Value Measures Of Assets And Liabilities) (Details) - USD ($) $ in Thousands		Dec. 31, 2023		Sep. 30, 2023
Assets:
Cash Equivalents – Money Market Mutual Funds	[1]	$ 32,781		$ 39,332
Derivative Financial Instruments:
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Fair Value of Derivative Financial Instruments		Fair Value of Derivative Financial Instruments
Total Assets	[1]	$ 251,514		$ 121,553
Derivative Financial Instruments:
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Fair Value of Derivative Financial Instruments		Fair Value of Derivative Financial Instruments
Total Liabilities	[1]	$ 0		$ 31,009
Total Net Assets/(Liabilities)	[1]	251,514		90,544
Over the Counter Swaps – Gas
Derivative Financial Instruments:
Derivative Asset	[1]	123,826		28,292
Derivative Financial Instruments:
Derivative Liability	[1]	0		30,803
Over the Counter No Cost Collars – Gas
Derivative Financial Instruments:
Derivative Asset		57,917	[1]	16,221
Derivative Financial Instruments:
Derivative Liability	[1]			205
Contingent Consideration for Asset Sale
Derivative Financial Instruments:
Derivative Asset	[1]	3,078		7,277
Foreign Currency Contracts
Derivative Financial Instruments:
Derivative Asset	[1]	(82)		(1,303)
Derivative Financial Instruments:
Derivative Liability	[1]	0		1
Balanced Equity Mutual Fund
Derivative Financial Instruments:
Other Investments	[1]	17,484		15,837
Fixed Income Mutual Fund
Derivative Financial Instruments:
Other Investments	[1]	16,510		15,897
Level 1
Assets:
Cash Equivalents – Money Market Mutual Funds		32,781		39,332
Derivative Financial Instruments:
Total Assets		66,775		71,066
Derivative Financial Instruments:
Total Liabilities		0		0
Total Net Assets/(Liabilities)		66,775		71,066
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
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		17,484		15,837
Level 1 | Fixed Income Mutual Fund
Derivative Financial Instruments:
Other Investments		16,510		15,897
Level 2
Assets:
Cash Equivalents – Money Market Mutual Funds		0		0
Derivative Financial Instruments:
Total Assets		202,048		104,193
Derivative Financial Instruments:
Total Liabilities		17,309		84,715
Total Net Assets/(Liabilities)		184,739		19,478
Level 2 | Over the Counter Swaps – Gas
Derivative Financial Instruments:
Derivative Asset		140,548		65,800
Derivative Financial Instruments:
Derivative Liability		16,722		68,311
Level 2 | Over the Counter No Cost Collars – Gas
Derivative Financial Instruments:
Derivative Asset		57,917		30,966
Derivative Financial Instruments:
Derivative Liability				14,950
Level 2 | Contingent Consideration for Asset Sale
Derivative Financial Instruments:
Derivative Asset		3,078		7,277
Level 2 | Foreign Currency Contracts
Derivative Financial Instruments:
Derivative Asset		505		150
Derivative Financial Instruments:
Derivative Liability		587		1,454
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
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
Netting Adjustments
Assets:
Cash Equivalents – Money Market Mutual Funds	[1]	0		0
Derivative Financial Instruments:
Total Assets	[1]	(17,309)		(53,706)
Derivative Financial Instruments:
Total Liabilities	[1]	(17,309)		(53,706)
Total Net Assets/(Liabilities)	[1]	0		0
Netting Adjustments | Over the Counter Swaps – Gas
Derivative Financial Instruments:
Derivative Asset	[1]	(16,722)		(37,508)
Derivative Financial Instruments:
Derivative Liability	[1]	(16,722)		(37,508)
Netting Adjustments | Over the Counter No Cost Collars – Gas
Derivative Financial Instruments:
Derivative Asset		0	[1]	(14,745)
Derivative Financial Instruments:
Derivative Liability	[1]			(14,745)
Netting Adjustments | Contingent Consideration for Asset Sale
Derivative Financial Instruments:
Derivative Asset	[1]	0		0
Netting Adjustments | Foreign Currency Contracts
Derivative Financial Instruments:
Derivative Asset	[1]	(587)		(1,453)
Derivative Financial Instruments:
Derivative Liability	[1]	(587)		(1,453)
Netting Adjustments | Balanced Equity Mutual Fund
Derivative Financial Instruments:
Other Investments	[1]	0		0
Netting Adjustments | Fixed Income Mutual Fund
Derivative Financial Instruments:
Other Investments	[1]	$ 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.