Supplementary Information for Exploration and Production Activities - Summary of Capitalized Costs of Unproved Properties Excluded from Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Acquisition Costs	$ 1,277	$ 8,136	$ 86,038
Development Costs	6,267	1,077	922
Exploration Costs	460	0	0
Capitalized Interest	0	0	0
Capitalized costs of unproved properties excluded from amortization, total	8,004	$ 9,213	$ 86,960
Capitalized Costs of Unproved Properties Cumulative Balance
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Acquisition Costs	103,508
Development Costs	8,464
Exploration Costs	460
Capitalized Interest	0
Capitalized costs of unproved properties excluded from amortization, total	$ 112,432
Costs Incurred Prior to Fiscal 2023
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Acquisition Costs				$ 8,057
Development Costs				198
Exploration Costs				0
Capitalized Interest				0
Capitalized costs of unproved properties excluded from amortization, total				$ 8,255