Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Balance Sheet) (Detail) - USD ($) $ in Millions		Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Derivative assets with affiliates	[1]	$ 51	$ 28
Dominion Energy
Related Party Transaction [Line Items]
Payable to affiliates		1	1
DES
Related Party Transaction [Line Items]
Payable to affiliates		22	30
SCANA Corporation
Related Party Transaction [Line Items]
Payable to affiliates		7	0
Public Service Company Of North Carolina Incorporated
Related Party Transaction [Line Items]
Payable to affiliates		12	0
Receivable from affiliates		0	60
Solar Affiliates [Member]
Related Party Transaction [Line Items]
Payable to affiliates		0	1
Nuclear Affiliates
Related Party Transaction [Line Items]
Receivable from affiliates		$ 0	$ 1

[1] Includes amounts recorded in other current assets of $8 million and $4 million as of December 31, 2022 and 2021, respectively, and amounts recorded in other deferred debits and other assets of $43 million and $24 million as of December 31, 2022 and 2021, respectively.