Supplementary Information for Exploration and Production Activities - Costs Incurred in Property Acquisition, Exploration and Development Activities (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Property Acquisition Costs:
Proved		$ 13,680	$ 17,069	$ 33,190
Unproved		18,826	19,526	129,061
Exploration Costs	[1]	21,562	53,519	10,055
Development Costs	[2]	443,311	429,151	553,469
Asset Retirement Costs		58,680	46,017	8,363
Total Property Acquisition Costs		556,059	565,282	734,138
Capitalized interest included in exploration costs		0	100	0
Capitalized interest included in development costs		$ 0	$ 700	$ 100

[1] Amounts for 2025, 2024 and 2023 include capitalized interest of zero, $0.1 million and zero  respectively.

[2] Amounts for 2025, 2024 and 2023 include capitalized interest of zero, $0.7 million and $0.1 million, respectively.