Supplementary Information for Oil and Gas Producing Activities - Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Supplementary Information for Oil and Gas Producing Activities Unaudited [Abstract]
Future Cash Inflows	$ 11,947,345	$ 19,209,099	$ 10,175,182
Less:
Future Production Costs	3,538,389	3,138,226	3,423,629
Future Development Costs	1,095,096	781,847	597,662
Future Income Tax Expense at Applicable Statutory Rate	1,867,457	3,876,272	1,397,175
Future Net Cash Flows	5,446,403	11,412,754	4,756,716
Less:
10% Annual Discount for Estimated Timing of Cash Flows	2,874,295	5,964,424	2,403,144
Standardized Measure of Discounted Future Net Cash Flows	$ 2,572,108	$ 5,448,330	$ 2,353,572	$ 1,222,470