Derivatives And Hedging (Schedule Of Derivative Instruments On The Statement Of Revenues, Expenses, And Patronage Capital) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Regulatory Asset/Liability for Derivatives	$ 49,713	$ (3,627)
Amount Of Gain (Loss) Reclassified from Regulatory Asset/Liability into Income	36,221	(37,503)
Natural Gas Future Contracts [Member] | Fuel [Member] | Operating Expense Fuel [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Regulatory Asset/Liability for Derivatives	34,703	(5,043)
Amount Of Gain (Loss) Reclassified from Regulatory Asset/Liability into Income	26,758	(37,242)
Financial Transmission Rights [Member] | Purchased Power [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Regulatory Asset/Liability for Derivatives	15,010	1,416
Amount Of Gain (Loss) Reclassified from Regulatory Asset/Liability into Income	$ 9,463	$ (261)