Commitments and Contingencies (Guarantees, Surety Bonds and Letters of Credit) (Detail)	Jun. 30, 2020 USD ($)
Guarantee Obligations [Line Items]
Maximum Exposure	$ 5,248,000,000	[1]
Commodity Transactions
Guarantee Obligations [Line Items]
Maximum Exposure	2,215,000,000	[2]
Nuclear Obligations
Guarantee Obligations [Line Items]
Maximum Exposure	224,000,000	[3]
Cove Point
Guarantee Obligations [Line Items]
Maximum Exposure	1,900,000,000	[4]
Financial Guarantee | Equity Method Investee [Member]
Guarantee Obligations [Line Items]
Maximum Exposure	27,000,000
Solar
Guarantee Obligations [Line Items]
Maximum Exposure	449,000,000	[5]
Other
Guarantee Obligations [Line Items]
Maximum Exposure	460,000,000	[6]
Surety Bond
Guarantee Obligations [Line Items]
Maximum Exposure	177,000,000
Surety Bond | Virginia Electric and Power Company
Guarantee Obligations [Line Items]
Maximum Exposure	89,000,000
Surety Bond | Dominion Energy Gas Holdings, LLC
Guarantee Obligations [Line Items]
Maximum Exposure	27,000,000
Financial Standby Letter of Credit
Guarantee Obligations [Line Items]
Maximum Exposure	$ 103,000,000

[1] Excludes Dominion Energy's guarantees for the new corporate office properties discussed in Note 15 to the Consolidated Financial Statements in the Companies’ Annual Report on Form 10-K for the year ended December 31, 2019 and in Note 14 in this report.

[2] Guarantees related to commodity commitments of certain subsidiaries. These guarantees were provided to counterparties in order to facilitate physical and financial transaction related commodities and services.

[3] Guarantees primarily related to certain DGI subsidiaries regarding all aspects of running a nuclear facility.

[4] Guarantees related to Cove Point, in support of terminal services, transportation and construction. Cove Point has two guarantees that have no maximum limit and, therefore, are not included in this amount.

[5] Includes guarantees to facilitate the development of solar projects. Also includes guarantees entered into by DGI on behalf of certain subsidiaries to facilitate the acquisition and development of solar projects.

[6] Guarantees related to other miscellaneous contractual obligations such as leases, environmental obligations, construction projects and insurance programs. Due to the uncertainty of workers’ compensation claims, the parental guarantee has no stated limit.