Wholesale Power Contracts (Schedule Of Revenues From Member Distribution Cooperatives) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Member distribution revenue	$ 1,024.3	$ 951.1	$ 726.9
Rappahannock Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	312.4	288.6	223.3
Shenandoah Valley Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	192.1	180.9	138.2
Delaware Electric Cooperative, Inc. [Member]
Related Party Transaction [Line Items]
Member distribution revenue	148.1	140.0	109.1
Choptank Electric Cooperative, Inc. [Member]
Related Party Transaction [Line Items]
Member distribution revenue	95.7	92.3	72.1
Southside Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	74.5	67.5	51.8
Mecklenburg Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	71.0	54.3	32.6
A&N Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	56.7	55.1	44.0
Prince George Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	27.0	25.8	20.2
Northern Neck Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	21.7	21.5	16.9
Community Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	13.9	13.9	10.5
BARC Electric Cooperative [Member]
Related Party Transaction [Line Items]
Member distribution revenue	$ 11.2	$ 11.2	$ 8.2