Employee Benefit Plans (Components of Provision for Net Periodic Benefit Cost (Credit)) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 22	$ 24	$ 44	$ 48
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		$ 108	$ 110	$ 217	$ 221
Expected return on plan assets		(207)	(216)	(411)	(432)
Amortization of net actuarial (gain) loss		(7)		(13)
Settlements and curtailments	[1]	4		4
Plan amendment				22
Net periodic benefit (credit) cost		(66)	(82)	(111)	(163)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 3	$ 4	$ 6	$ 7
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		$ 14	$ 16	$ 28	$ 31
Expected return on plan assets		(43)	(38)	(85)	(76)
Amortization of prior service cost (credit)		(9)	(9)	(18)	(18)
Amortization of net actuarial (gain) loss		(2)	(2)	(4)	(3)
Net periodic benefit (credit) cost		$ (37)	$ (29)	$ (73)	$ (59)

[1] 2024 amount relates to Dominion Energy nonqualified pension plan.