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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, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Pension Benefits |  |  |  |
Service cost |  | $ 142 | $ 170 | $ 173
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 |  | $ 333 | $ 317 | $ 351
Expected return on plan assets |  | (886) | (834) | (777)
Amortization of prior service (credit) cost |  |  |  | 1
Amortization of net actuarial loss |  | 159 | 193 | 206
Settlements, curtailments and special termination benefits | [1] |  | 10 | 14
Net periodic benefit (credit) cost |  | (252) | (144) | (32)
Changes in plan assets and benefit obligations recognized in other comprehensive income and regulatory assets and liabilities: |  |  |  |
Current year net actuarial (gain) loss |  | 726 | (782) | 166
Settlements and curtailments | [1] | (3) | (36) | (81)
Amortization of net actuarial gain (loss) |  | (159) | (193) | (206)
Amortization of prior service credit (cost) |  |  |  | (1)
Sale of hope |  | (47) |  |
Total recognized in other comprehensive income and regulatory assets and liabilities |  | $ 517 | $ (1,011) | $ (122)
Significant assumptions used to determine periodic cost: |  |  |  |
Weighted average rate of increase for compensation |  | 4.51% | 4.53% | 4.23%
Pension Benefits | Minimum |  |  |  |
Significant assumptions used to determine periodic cost: |  |  |  |
Discount rate |  | 3.06% | 2.73% | 2.77%
Expected long-term rate of return on plan assets |  | 7.00% | 7.00% | 7.00%
Crediting interest rate for cash balance and similar plans |  | 1.81% | 1.93% | 2.31%
Pension Benefits | Maximum |  |  |  |
Significant assumptions used to determine periodic cost: |  |  |  |
Discount rate |  | 3.19% | 3.29% | 3.63%
Expected long-term rate of return on plan assets |  | 8.35% | 8.45% | 8.60%
Crediting interest rate for cash balance and similar plans |  | 1.94% | 2.15% | 2.83%
Other Postretirement Benefits |  |  |  |
Service cost |  | $ 22 | $ 25 | $ 28
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 |  | $ 45 | $ 46 | $ 58
Expected return on plan assets |  | (191) | (173) | (156)
Amortization of prior service (credit) cost |  | (38) | (42) | (49)
Amortization of net actuarial loss |  | (2) | 4 | 6
Settlements, curtailments and special termination benefits | [1] | (8) |  | (59)
Net periodic benefit (credit) cost |  | (172) | (140) | (172)
Changes in plan assets and benefit obligations recognized in other comprehensive income and regulatory assets and liabilities: |  |  |  |
Current year net actuarial (gain) loss |  | 246 | (282) | (110)
Prior service (credit) cost |  |  | (13) | (6)
Settlements and curtailments | [1] | 10 |  | 59
Amortization of net actuarial gain (loss) |  | 2 | (4) | (6)
Amortization of prior service credit (cost) |  | 38 | 42 | 49
Total recognized in other comprehensive income and regulatory assets and liabilities |  | $ 296 | $ (257) | $ (14)
Significant assumptions used to determine periodic cost: |  |  |  |
Expected long-term rate of return on plan assets |  | 8.35% | 8.45% | 8.50%
Health care cost trend rate | [2] | 6.25% | 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%
Other Postretirement Benefits | Minimum |  |  |  |
Significant assumptions used to determine periodic cost: |  |  |  |
Discount rate |  | 3.04% | 2.69% | 3.07%
Year that the rate reaches the ultimate trend rate | [2] | 2026 | 2026 | 2025
Other Postretirement Benefits | Maximum |  |  |  |
Significant assumptions used to determine periodic cost: |  |  |  |
Discount rate |  | 5.03% | 2.80% | 3.52%
Year that the rate reaches the ultimate trend rate | [2] | 2027 | 2027 | 2026
[1] | 2022 amounts relate primarily to Dominion Energy’s sale of Hope. 2021 amounts relate primarily to the Dominion Energy executive nonqualified pension plan. 2020 amounts primarily relate to the GT&S Transaction.
[2] | Assumptions used to determine net periodic cost for the following year.

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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 8 -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e2919-114920 + Details
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- Definition Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(2) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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