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Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 6 Months Ended 12 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Mar. 31, 2022
Mar. 31, 2021
Sep. 30, 2021
Sep. 30, 2022
Summary Of Significant Accounting Policies [Line Items]            
Gas Stored Underground $ 6,302   $ 6,302   $ 33,669  
Capitalized Costs Oil and Gas Producing Activities Net $ 2,000,000   2,000,000   1,900,000  
Capitalized costs of unproved properties excluded from amortization     $ 124,200   103,800  
Full cost ceiling test discount factor 10.00%   10.00%      
Amount Full Cost Ceiling Exceeds Book Value Of Oil And Gas Properties $ 1,800,000   $ 1,800,000      
Decrease estimated future net cash flows (452,500)          
Other Post-Retirement Adjustment for Regulatory Proceeding (7,351) $ 0 (7,351) $ 0    
Other Post-Retirement Adjustment for Regulatory Proceeding After Tax $ (5,807)   $ (5,807)      
Antidilutive securities 13,815 334,945 11,883 334,945    
Reserve For Gas Replacement [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Gas Stored Underground $ 43,752   $ 43,752   $ 0  
Restricted Stock Units [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Share based compensation other than options grants in period     128,050      
Granted in fiscal year, weighted average grant date fair value     $ 54.06      
Performance Shares [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Share based compensation other than options grants in period     195,397      
Granted in fiscal year, weighted average grant date fair value     $ 65.39      
Subsequent Event [Member] | Reserve For Gas Replacement [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Gas Stored Underground           $ 0