Summary Of Significant Accounting Policies - (Schedule of Operating Revenues) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Energy revenues Formula rate	$ 571,109	$ 540,423	$ 328,045
Renewable energy credits Formula rate	375	259	36
Demand revenues Formula rate	431,399	410,437	398,819
Total Formula rate revenues	1,002,883	951,119	726,900
Energy revenues Market-based rates	18,880
Demand revenues Market-based rates	2,568
Total Market-based rates revenues	21,448
Total Member distribution cooperatives revenues	1,024,331	951,119	726,900
Energy revenues	33,760	42,818	45,255
Renewable energy credits	24,300	11,980	8,485
Total Non-members revenues	58,060	54,798	53,740
Total operating revenues	$ 1,082,391	$ 1,005,917	$ 780,640
Type Of Revenue Extensible List	us-gaap:ElectricityMember	us-gaap:ElectricityMember	us-gaap:ElectricityMember