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Supplementary Information for Exploration and Production Activities - Summary of Capitalized Costs of Unproved Properties Excluded from Amortization (Details) - USD ($) $ in Thousands | 12 Months Ended
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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

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- Definition Amount of capitalized acquisition cost incurred during period and excluded from amortization for oil- and gas-producing activities accounted for under full cost method. Excludes exploration and development costs and capitalized interest. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 932 -SubTopic 360 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477385/932-360-S50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 932 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10(c)(7)(ii)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479664/932-10-S99-1 + Details
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- Definition Amount of capitalized acquisition, exploration, and development costs and capitalized interest incurred during period and excluded from amortization for oil- and gas-producing activities accounted for under full cost method. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 932 -SubTopic 360 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477385/932-360-S50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 932 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10(c)(7)(ii)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479664/932-10-S99-1 + Details
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- Definition Amount of capitalized development cost incurred during period and excluded from amortization for oil- and gas-producing activities accounted for under full cost method. Excludes acquisition and exploration costs and capitalized interest. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 932 -SubTopic 360 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477385/932-360-S50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 932 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10(c)(7)(ii)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479664/932-10-S99-1 + Details
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- Definition Amount of capitalized exploration cost incurred during period and excluded from amortization for oil- and gas-producing activities accounted for under full cost method. Excludes acquisition and development costs and capitalized interest. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 932 -SubTopic 360 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477385/932-360-S50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 932 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10(c)(7)(ii)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479664/932-10-S99-1 + Details
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