Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Balance Sheet) (Detail) - USD ($) $ in Millions		Jun. 30, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Derivative assets with affiliates	[1]	$ 33	$ 51
Solar Affiliates [Member]
Related Party Transaction [Line Items]
Payable to affiliates		2	0
Dominion Energy
Related Party Transaction [Line Items]
Payable to affiliates		1	1
DES
Related Party Transaction [Line Items]
Payable to affiliates		17	22
SCANA Corporation
Related Party Transaction [Line Items]
Payable to affiliates		7	7
Public Service Company Of North Carolina Incorporated
Related Party Transaction [Line Items]
Payable to affiliates		$ 7	$ 12

[1] Includes amounts recorded in other current assets of $2 million and $8 million as of June 30, 2023 and December 31, 2022, respectively, and amounts recorded in other deferred debits and other assets of $31 million and $43 million as of June 30, 2023 and December 31, 2022, respectively.