Wholesale Power Contracts - Additional Information (Details)	12 Months Ended
	Dec. 31, 2024 MW	Dec. 31, 2023 Member MW
Wholesale Power Contracts [Line Items]
Required period for termination of wholesale power contract		3 years
Purchases under limited contract exceptions, percent of power received from owned generation or other suppliers		5.00%
Description of limited exceptions		There are two additional exceptions to the all-requirements nature of our wholesale power contracts. One exception permits each of our member distribution cooperatives, with 180 days prior written notice, to receive up to the greater of
Prior written notice period		180 days
Purchases under limited contract exceptions, amount of power allowable under contractual exception received from owned generation or other suppliers		5
Removal of load requirements under exception		129
Current reduction in demand and associated energy related to limited exception if fully utilized		182
Forecast [Member]
Wholesale Power Contracts [Line Items]
Return of load requirements under exception	110
Maximum [Member]
Wholesale Power Contracts [Line Items]
Exception for purchases of hydroelectric power allocated from SEPA		2.00%
Mainland Virginia [Member]
Wholesale Power Contracts [Line Items]
Principal exceptions to the all-requirements obligations by members | Member		8