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, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Supplementary Information For Oil And Gas Producing Activities Unaudited [Abstract]
Future Cash Inflows	$ 10,175,182	$ 6,493,362	$ 8,738,182
Future Production Costs	3,423,629	3,149,857	2,989,518
Future Development Costs	597,662	501,678	797,640
Future Income Tax Expense at Applicable Statutory Rate	1,397,175	454,553	1,159,882
Future Net Cash Flows	4,756,716	2,387,274	3,791,142
10% Annual Discount for Estimated Timing of Cash Flows	2,403,144	1,164,804	2,054,823
Standardized Measure of Discounted Future Net Cash Flows	$ 2,353,572	$ 1,222,470	$ 1,736,319	$ 1,720,305