Employee Benefit Plans (Net Periodic Benefit (Credit) Cost and Amounts Recognized in Other Comprehensive Income and Regulatory Assets and Liabilities) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits
Service cost		$ 96	$ 142	$ 170
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Interest cost		$ 442	$ 333	$ 317
Expected return on plan assets		(864)	(886)	(834)
Amortization of net actuarial (gain) loss			159	193
Settlements, curtailments and special termination benefits	[1]	1		10
Net periodic benefit (credit) cost		(325)	(252)	(144)
Changes in plan assets and benefit obligations recognized in other comprehensive income and regulatory assets and liabilities:
Current year net actuarial (gain) loss		304	726	(782)
Prior service (credit) cost		2
Settlements and curtailments	[1]		(3)	(36)
Amortization of net actuarial gain (loss)			(159)	(193)
Sale of hope			(47)
Total recognized in other comprehensive income and regulatory assets and liabilities		$ 306	$ 517	$ (1,011)
Significant assumptions used to determine periodic cost:
Weighted average rate of increase for compensation		4.38%	4.51%	4.53%
Pension Benefits | Minimum
Significant assumptions used to determine periodic cost:
Discount rate		5.65%	3.06%	2.73%
Expected long-term rate of return on plan assets		7.00%	7.00%	7.00%
Crediting interest rate for cash balance and similar plans		4.40%	1.81%	1.93%
Pension Benefits | Maximum
Significant assumptions used to determine periodic cost:
Discount rate		5.75%	3.19%	3.29%
Expected long-term rate of return on plan assets		8.35%	8.35%	8.45%
Crediting interest rate for cash balance and similar plans		4.50%	1.94%	2.15%
Other Postretirement Benefits
Service cost		$ 14	$ 22	$ 25
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Interest cost		$ 61	$ 45	$ 46
Expected return on plan assets		(151)	(191)	(173)
Amortization of prior service (credit) cost		(36)	(38)	(42)
Amortization of net actuarial (gain) loss		(6)	2	4
Settlements, curtailments and special termination benefits	[1]		(8)
Net periodic benefit (credit) cost		(118)	(172)	(140)
Changes in plan assets and benefit obligations recognized in other comprehensive income and regulatory assets and liabilities:
Current year net actuarial (gain) loss		(125)	246	(282)
Prior service (credit) cost				(13)
Settlements and curtailments	[1]		10
Amortization of net actuarial gain (loss)		6	2	(4)
Amortization of prior service credit (cost)		36	38	42
Total recognized in other comprehensive income and regulatory assets and liabilities		$ (83)	$ 296	$ (257)
Significant assumptions used to determine periodic cost:
Expected long-term rate of return on plan assets		8.35%	8.35%	8.45%
Health care cost trend rate	[2]	7.00%	6.25%	6.25%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	[2]	5.00%	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	[2]	2030
Other Postretirement Benefits | Minimum
Significant assumptions used to determine periodic cost:
Discount rate		5.69%	3.04%	2.69%
Year that the rate reaches the ultimate trend rate	[2]		2026	2026
Other Postretirement Benefits | Maximum
Significant assumptions used to determine periodic cost:
Discount rate		5.70%	5.03%	2.80%
Year that the rate reaches the ultimate trend rate	[2]		2027	2027

[1] 2023 and 2021 amounts relate primarily to the Dominion Energy executive nonqualified pension plan. 2022 amounts relate primarily to Dominion Energy’s sale of Hope.

[2] Assumptions used to determine net periodic cost for the following year.