Property, Plant and Equipment (Narrative) (Detail) $ in Millions		3 Months Ended			12 Months Ended
		Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($) MVA
Property, Plant and Equipment [Line Items]
Noncontrolling Interests			$ 46	$ 0
Income tax expense (benefit)	[1]		55	55
Virginia Electric and Power Company
Property, Plant and Equipment [Line Items]
Noncontrolling Interests			46	0
Income tax expense (benefit)	[2]		92	$ 128
Virginia Electric and Power Company | CVOW Commercial Project
Property, Plant and Equipment [Line Items]
Anticipated projected cost			100
Ownership percentage					50.00%
Charge for costs not expected to be recovered			45
Noncontrolling Interests			22
Income tax expense (benefit)			$ (6)
Percentage of remaining construction costs, including contingency			6.00%
Virginia Electric and Power Company | CVOW Commercial Project | End of 2026
Property, Plant and Equipment [Line Items]
Targeted capacity provided by legislation | MVA					2.6
Anticipated projected cost					$ 10,800
Virginia Electric and Power Company | CVOW Commercial Project | End of 2026 | Maximum
Property, Plant and Equipment [Line Items]
Anticipated projected cost			$ 400
Virginia Electric and Power Company | CVOW Commercial Project | Scenario Forecast
Property, Plant and Equipment [Line Items]
Charge for costs not expected to be recovered		$ 15
Noncontrolling Interests		$ 8

[1] The significant expense categories and amounts in the segment information presented above align with the segment-level information that is regularly provided to Dominion Energy’s CODM.

[2] The significant expense categories and amounts in the segment information presented above align with the segment-level information that is regularly provided to Virginia Power’s CODM.