Significant Accounting Policies (Narrative) (Detail 1)	1 Months Ended				3 Months Ended						12 Months Ended
	Feb. 29, 2024 USD ($)	Jan. 31, 2024 USD ($) $ / shares	Jan. 31, 2022 USD ($) $ / shares	Sep. 30, 2019 USD ($)	Dec. 31, 2024 USD ($) MWh $ / shares	Sep. 30, 2024 $ / shares	Jun. 30, 2024 $ / shares	Mar. 31, 2024 $ / shares	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($) $ / shares	Dec. 31, 2024 USD ($) MWh	Dec. 31, 2023 USD ($) MWh $ / shares	Dec. 31, 2022 USD ($) MWh
Significant Accounting Policies [Line Items]
Margin deposit assets					$ 104,000,000						$ 104,000,000	$ 38,000,000
Margin liabilities					$ 3,000,000						3,000,000	15,000,000
Impairment of assets and other charges											$ 600,000,000	$ 307,000,000	$ 1,401,000,000
Increase in EPS | $ / shares					$ (0.03)	$ (0.01)	$ (0.01)	$ (0.28)
Finite Lived Intangible Asset Useful Life					35 years						35 years
Estimated proved developed or proved gas and oil reserves rate per unit | MWh					1.83						1.83	1.73	1.67
Cost saving incentive											$ 0	$ 4,000,000	$ 27,000,000
Non-jurisdictional and Certain Nonutility Solar Generation Facilities
Significant Accounting Policies [Line Items]
Finite Lived Intangible Asset Useful Life			35 years
Change in Depreciation Rates from New Depreciation Study
Significant Accounting Policies [Line Items]
Increase in EPS | $ / shares										$ 0.05
Revision of Estimated Useful Life | Non-jurisdictional and Certain Nonutility Solar Generation Facilities
Significant Accounting Policies [Line Items]
Increase (decrease) in depreciation expense		$ (17,000,000)	$ (16,000,000)									(35,000,000)
Increase (decrease) in depreciation expense, after tax		$ (13,000,000)	$ (12,000,000)									$ (26,000,000)
Increase in EPS | $ / shares		$ 0.02	$ 0.02									$ 0.03
Virginia Electric and Power Company
Significant Accounting Policies [Line Items]
Percentage of fuel currently subject to deferred fuel accounting											87.00%
Estimated under-recovered balances	$ 1,300,000,000										$ 1,300,000,000
Margin deposit assets					$ 1,000,000						1,000,000	$ 35,000,000
Margin liabilities					0						0	0
AFUDC recorded as regulatory asset					$ 3,000,000						$ 3,000,000		34,000,000
Finite Lived Intangible Asset Useful Life					35 years						35 years
Percentage of remaining construction costs, including contingency					5.00%						5.00%
Expected disallowance charge					$ 103,000,000
Expected disallowance charge after tax					77,000,000
Virginia Electric and Power Company | Rider OSW
Significant Accounting Policies [Line Items]
Anticipated projected cost					600,000,000						$ 600,000,000
Increase for increased contingency for remaining construction activities											300,000,000
Virginia Electric and Power Company | CVOW Commercial Project
Significant Accounting Policies [Line Items]
Anticipated projected cost				$ 600,000,000	$ 10,700,000,000						$ 10,700,000,000
Increase for increased contingency for remaining construction activities				$ 300,000,000
Percentage of remaining construction costs, including contingency					5.00%						5.00%
Virginia Electric and Power Company | Change in Depreciation Rates from New Depreciation Study
Significant Accounting Policies [Line Items]
Increase (decrease) in depreciation expense										$ (60,000,000)
Increase (decrease) in depreciation expense, after tax										$ (45,000,000)
Virginia Electric and Power Company | Revision of Estimated Useful Life
Significant Accounting Policies [Line Items]
Increase (decrease) in depreciation expense			$ (6,000,000)
Increase (decrease) in depreciation expense, after tax			$ (4,000,000)
Virginia Electric and Power Company | Electric Generation Facilities
Significant Accounting Policies [Line Items]
Charges recorded with dismantling											$ 40,000,000	25,000,000	167,000,000
Charges recorded with dismantling after tax											30,000,000	19,000,000	$ 124,000,000
Virginia Electric and Power Company | Maximum
Significant Accounting Policies [Line Items]
AFUDC recorded as regulatory asset												1,000,000
Virginia Electric and Power Company | Impairment of Assets and Other Charges
Significant Accounting Policies [Line Items]
Impairment of assets and other charges									$ 191,000,000		25,000,000
Impairment of assets and other charges after tax									$ 142,000,000		18,000,000
Virginia Electric and Power Company | Affiliated Entity
Significant Accounting Policies [Line Items]
Income taxes receivable					$ 26,000,000						26,000,000	40,000,000
Virginia Electric and Power Company | Affiliated Entity | Federal
Significant Accounting Policies [Line Items]
Income taxes receivable					21,000,000						21,000,000	45,000,000
Virginia Electric and Power Company | Affiliated Entity | State
Significant Accounting Policies [Line Items]
Income taxes receivable					$ 5,000,000						$ 5,000,000
Income taxes payable												$ 5,000,000