Operating Revenue (Disaggregation of Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Total Operating Revenues	[1]	$ 832	$ 731	$ 1,818	$ 1,506
Electric Operations
Operating revenue from contracts with customers		728	627	1,468	1,213
Other revenues		7	7	13	14
Total Operating Revenues		735	634	1,481	1,227
Gas Distribution
Operating revenue from contracts with customers		96	96	336	278
Other revenues		1	1	1	1
Total Operating Revenues		97	97	337	279
Residential | Electric Operations
Operating revenue from contracts with customers		346	294	717	577
Residential | Gas Distribution
Operating revenue from contracts with customers		55	48	206	165
Commercial | Electric Operations
Operating revenue from contracts with customers		235	208	463	396
Commercial | Gas Distribution
Operating revenue from contracts with customers		26	25	80	66
Industrial | Electric Operations
Operating revenue from contracts with customers		112	94	221	181
Industrial | Gas Distribution
Operating revenue from contracts with customers		3	17	30	35
Other | Electric Operations
Operating revenue from contracts with customers		35	31	67	59
Other | Gas Distribution
Operating revenue from contracts with customers		$ 12	$ 6	$ 20	$ 12

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