This item represents the entity's aggregate generation capacity from long-term power and capacity contracts.

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Costs incurred in purchasing electric capacity.

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Long Term Capacity Contract Non Utility Generators.

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Shared Services Purchased.

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Variable Interest Entities Payments For Contract Termination.

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Variable interest entities payments for contract termination after tax.

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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

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Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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Variable Interest Entities - (Narrative) (Detail) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	May 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) MW Generators	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Feb. 29, 2020
Atlantic Coast Pipeline
Variable Interest Entity [Line Items]
Percentage of ownership interest acquired						5.00%
Southern Company Gas \| Dominion Energy Midstream Partners, LP \| Atlantic Coast Pipeline
Variable Interest Entity [Line Items]
Minority Interest Ownership Percentage By Parent						53.00%
Variable Interest Entity, Primary Beneficiary \| Partnership Interest \| Merchant Solar Projects
Variable Interest Entity [Line Items]
Initial membership interest percentage			67.00%
Variable Interest Entity, Not Primary Beneficiary \| Gas Distribution \| Atlantic Coast Pipeline \| Pipelines \| Jointly Owned Natural Gas Pipeline
Variable Interest Entity [Line Items]
Initial membership interest percentage			48.00%
SBL Holdco \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Securities due within one year			$ 31
Long term debt			267
Virginia Electric and Power Company
Variable Interest Entity [Line Items]
Securities due within one year			4	$ 350
Long term debt			12,325	11,320
Payables to affiliates			210	209
Virginia Electric and Power Company \| Variable Interest Entity, Not Primary Beneficiary \| DES
Variable Interest Entity [Line Items]
Payables to affiliates			102	107
Shared Services Purchased			$ 387	119	$ 335
Virginia Electric and Power Company \| Variable Interest Entity (VIE) or Potential VIE, Information Unavailability
Variable Interest Entity [Line Items]
Long term capacity contract non utility generators (generators) \| Generators			1
Aggregate generation capacity from long-term power and capacity contracts (MW) \| MW			218
Payment for electric capacity			$ 13	50	86
Payment for electric energy			1	18	24
Payment for contract termination	$ 135	$ 135
Payment for contract termination after tax		$ 100
Dominion Energy Gas Holdings, LLC
Variable Interest Entity [Line Items]
Securities due within one year			700	748
Long term debt			4,821	7,022
Payables to affiliates			$ 82	124
Dominion Energy Gas Holdings, LLC \| Dominion Energy Midstream Partners, LP
Variable Interest Entity [Line Items]
Percentage of limited partner interests in Cove Point			75.00%
Minority Interest Ownership Percentage By Parent			25.00%
Dominion Energy Gas Holdings, LLC \| Variable Interest Entity, Not Primary Beneficiary \| DES
Variable Interest Entity [Line Items]
Payables to affiliates			$ 27	43
Shared Services Purchased			106	340	106
Dominion Energy Gas Holdings, LLC \| Variable Interest Entity, Not Primary Beneficiary \| DECGS And DEQPS
Variable Interest Entity [Line Items]
Payables to affiliates			15	6
Shared Services Purchased			$ 49	$ 45	$ 45