Equity (Schedule of Changes in AOCI Net of Tax and Reclassifications out of AOCI by Component) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance		$ 27,659
Total other comprehensive income		66	$ (114)	$ 259
Ending balance		27,529	27,659
Virginia Electric and Power Company
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance		16,949	15,787	14,557
Total other comprehensive income		7	50	11
Ending balance		21,657	16,949	15,787
Total Derivative-Hedging Activities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	[1],[2]	(249)	(358)
Other comprehensive income before reclassifications: gains (losses)	[1],[2]		67
Total other comprehensive income	[1],[2]	33	109
Ending balance	[1],[2]	(216)	(249)	(358)
Total Derivative-Hedging Activities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	[1],[3]	16	(45)
Other comprehensive income before reclassifications: gains (losses)	[1],[3]	(1)	60
Income (loss) before income tax expense	[1],[3]	1
Total other comprehensive income	[1],[3]		61
Ending balance	[1],[3]	15	16	(45)
Total Derivative-Hedging Activities | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income Loss [Line Items]
Interest and related charges	[1],[2]	43	57
Income (loss) before income tax expense	[1],[2]	43	57
Income tax expense (benefit)	[1],[2]	10	(15)
Total, net of tax	[1],[2]	33	42
Total Derivative-Hedging Activities | Amounts reclassified from AOCI | Virginia Electric and Power Company
Accumulated Other Comprehensive Income Loss [Line Items]
Interest and related charges	[1],[3]	1	2
Income (loss) before income tax expense	[1],[3]		2
Income tax expense (benefit)	[1],[3]	1	1
Total, net of tax	[1],[3]		1
Total other comprehensive income	[1],[3]	(1)
Investment Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	[4]	(44)	37
Other comprehensive income before reclassifications: gains (losses)	[4]	55	100
Total other comprehensive income	[4]	44	(81)
Ending balance	[4]		(44)	37
Investment Securities | Virginia Electric and Power Company
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	[5]	(7)	4
Other comprehensive income before reclassifications: gains (losses)	[5]	7	(11)
Income (loss) before income tax expense	[5]	1
Total, net of tax	[5]	1
Total other comprehensive income	[5]	8	(11)
Ending balance	[5]	(1)	(7)	4
Investment Securities | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income Loss [Line Items]
Other income (expense)	[4]	(14)	25
Income (loss) before income tax expense	[4]	(14)	25
Income tax expense (benefit)	[4]	(3)	(6)
Total, net of tax	[4]	(11)	19
Investment Securities | Amounts reclassified from AOCI | Virginia Electric and Power Company
Accumulated Other Comprehensive Income Loss [Line Items]
Other income (expense)	[5]	1
Pension and Other Postretirement Benefit Costs
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	[6]	(1,276)	(1,133)
Other comprehensive income before reclassifications: gains (losses)	[6]	27	(218)
Total other comprehensive income	[6]	(14)	(143)
Ending balance	[6]	(1,290)	(1,276)	(1,133)
Pension and Other Postretirement Benefit Costs | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income Loss [Line Items]
Other income (expense)	[6]	(61)	102
Income (loss) before income tax expense	[6]	(61)	102
Income tax expense (benefit)	[6]	(20)	(27)
Total, net of tax	[6]	(41)	75
Equity Method Investees
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	[7]	(3)	(4)
Other comprehensive income before reclassifications: gains (losses)	[7]		1
Total other comprehensive income	[7]	3	1
Ending balance	[7]		(3)	(4)
Equity Method Investees | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income Loss [Line Items]
Discontinued operations	[7]	4
Income (loss) before income tax expense	[7]	4
Income tax expense (benefit)	[7]	1
Total, net of tax	[7]	3
AOCI
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance		(1,572)	(1,458)
Other comprehensive income before reclassifications: gains (losses)		82	(250)
Total other comprehensive income		66	(114)	259
Ending balance		(1,506)	(1,572)	(1,458)
AOCI | Virginia Electric and Power Company
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance		9	(41)	(52)
Other comprehensive income before reclassifications: gains (losses)		6	49
Income (loss) before income tax expense		2
Income tax expense (benefit)		(1)
Total, net of tax		1
Total other comprehensive income		7	50	11
Ending balance		16	9	$ (41)
AOCI | Amounts reclassified from AOCI
Accumulated Other Comprehensive Income Loss [Line Items]
Interest and related charges		43	57
Other income (expense)		(75)	127
Discontinued operations		4
Income (loss) before income tax expense		(28)	184
Income tax expense (benefit)		(12)	(48)
Total, net of tax		(16)	136
AOCI | Amounts reclassified from AOCI | Virginia Electric and Power Company
Accumulated Other Comprehensive Income Loss [Line Items]
Interest and related charges		1	2
Other income (expense)		$ 1
Income (loss) before income tax expense			2
Total, net of tax			$ 1

[1] Comprised entirely of interest rate derivative hedging activities.

[2] Net of $73 million, $83 million and $119 million tax at December 31, 2023, 2022 and 2021, respectively.

[3] Net of $(5) million, $(5) million and $16 million tax at December 31, 2023, 2022 and 2021, respectively.

[4] Net of $(2) million, $13 million and $(10) million tax at December 31, 2023 and 2022 and 2021, respectively.

[5] Net of $— million, $2 million and $(2) million tax at December 31, 2023, 2022 and 2021, respectively.

[6] Net of $456 million, $445 million and $396 million tax at December 31, 2023 and 2022 and 2021, respectively.

[7] Net of $— million, $1 million, and $1 million tax at December 31, 2023, 2022 and 2021, respectively.