Regulatory Assets and Liabilities (Narrative) (Detail) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Public Utilities General Disclosures [Line Items]
Regulatory assets not expect to earn return	$ 400
Aggregate regulatory assets	$ 9,615	$ 10,148
Period for which expenditures are expected to be recovered	2 years
Pension and Other Postretirement Benefit Plan Assets and Obligations \| East Ohio, PSNC and Questar Gas Transactions
Public Utilities General Disclosures [Line Items]
Aggregate regulatory assets	$ 308	302
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Regulatory assets not expect to earn return	2,700
Aggregate regulatory assets	$ 4,971	$ 5,387
Period for which expenditures are expected to be recovered	2 years

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

+ References

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Remaining balance of regulatory assets for which no return on investment during recovery is provided. In some cases, a regulator may permit an enterprise to include a cost that would be charged to expense by an unregulated enterprise as an allowable cost over a period of time by amortizing that cost for rate-making purposes, but the regulator does not include the unrecovered amount in the rate base.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 340
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481878/980-340-50-1

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-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 55
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481849/980-340-55-2

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Remaining recovery period of regulatory assets for which no return on investment during recovery period is provided, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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