Derivatives and Hedge Accounting Activities (Narrative) (Detail) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative instruments designated in fair value hedges	$ 0	$ 0	$ 0
Virginia Power
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative instruments designated in fair value hedges	$ 0	$ 0

Net fair value of all derivative instruments designated as fair value hedging instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-SubTopic 10
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480463/815-10-45-5

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant