Derivatives And Hedging (Schedule Of Derivative Instruments On The Statement Of Revenues, Expenses, And Patronage Capital) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Regulatory Asset/Liability for Derivatives	$ 124,712	$ 3,799
Amount Of Gain (Loss) Reclassified from Regulatory Asset/Liability into Income	22,353	(753)
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	116,238	3,711
Amount Of Gain (Loss) Reclassified from Regulatory Asset/Liability into Income	20,422	(4,365)
Financial Transmission Rights [Member] | Purchased Power [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Regulatory Asset/Liability for Derivatives	8,474	88
Amount Of Gain (Loss) Reclassified from Regulatory Asset/Liability into Income	$ 1,931	$ 3,612