Revenue Recognition (Disaggregation of Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Total Operating Revenues	[1]	$ 704	$ 909	$ 1,463	$ 1,758
Electric Operations
Operating revenue from contracts with customers		605	774	1,184	1,421
Other revenues		9	6	12	14
Total Operating Revenues		614	780	1,196	1,435
Gas Distribution
Operating revenue from contracts with customers		89	129	266	323
Other revenues		1		1
Total Operating Revenues		90	129	267	323
Residential | Electric Operations
Operating revenue from contracts with customers		266	332	528	632
Residential | Gas Distribution
Operating revenue from contracts with customers		43	45	152	154
Commercial | Electric Operations
Operating revenue from contracts with customers		208	245	395	446
Commercial | Gas Distribution
Operating revenue from contracts with customers		25	35	67	83
Industrial | Electric Operations
Operating revenue from contracts with customers		97	135	188	243
Industrial | Gas Distribution
Operating revenue from contracts with customers		15	43	37	74
Other | Electric Operations
Operating revenue from contracts with customers		34	62	73	100
Other | Gas Distribution
Operating revenue from contracts with customers		$ 6	$ 6	$ 10	$ 12

[1] See Note 12 for amounts attributable to affiliates.