Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023	Sep. 30, 2024
Summary Of Significant Accounting Policies [Line Items]
Gas Stored Underground	$ 26,891		$ 32,509
Capitalized Costs Oil and Gas Producing Activities Net	2,500,000		2,400,000
Capitalized costs of unproved properties excluded from amortization	$ 159,100		$ 161,100
Full cost ceiling test discount factor (as a percent)	10.00%
Amount Full Cost Ceiling Exceeds Book Value Of Oil And Gas Properties	$ 84,400
Increase estimated future net cash flows	$ 307,000
Antidilutive securities (in shares)	0	1,987
Reserve For Gas Replacement
Summary Of Significant Accounting Policies [Line Items]
Gas Stored Underground	$ 1,200
Restricted Stock Units
Summary Of Significant Accounting Policies [Line Items]
Share based compensation other than options grants in period (in shares)	219,578
Granted in fiscal year, weighted average grant date fair value (in USD per share)	$ 42.44
Performance Shares
Summary Of Significant Accounting Policies [Line Items]
Share based compensation other than options grants in period (in shares)	361,729
Granted in fiscal year, weighted average grant date fair value (in USD per share)	$ 44.23
Greenhouse gas emissions reductions, performance cycle	3 years
Performance Shares | Minimum
Summary Of Significant Accounting Policies [Line Items]
Return on capital, performance cycle (in years)	3 years
Relative shareholder return, performance cycle	3 years
Performance Shares | Maximum
Summary Of Significant Accounting Policies [Line Items]
Return on capital, performance cycle (in years)	5 years
Relative shareholder return, performance cycle	5 years
Subsequent Event | Reserve For Gas Replacement
Summary Of Significant Accounting Policies [Line Items]
Gas Stored Underground				$ 0