Affiliated and Related Party Transactions (Schedule of Affiliated Transactions - Income Statement) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Operating Revenues – Electric from sales to affiliate		$ 4	$ 4	$ 4
Operating Revenues – Gas from sales to affiliate		1	1	1
Operating Expenses – Other taxes from affiliate		8	8	7
DES and DESS
Related Party Transaction [Line Items]
Direct and allocated costs	[1]	222	212	226
Solar Affiliates [Member]
Related Party Transaction [Line Items]
Purchases from affiliate		$ 13	$ 14	$ 14

[1] Includes capitalized expenditures of $59 million, $48 million and $37 million for the years ended December 31, 2023, 2022 and 2021, respectively.