Operating Revenue (Disaggregation of Revenue) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating revenue from contracts with customers		$ 0	$ 0	$ 1
Total Operating Revenues	[1]	3,783	3,146	2,739
Electric Operations
Operating revenue from contracts with customers		3,079	2,626	2,337
Other revenues		27	13	15
Total Operating Revenues		3,106	2,639	2,352
Gas Distribution
Operating revenue from contracts with customers		676	506	387
Other revenues		1	1	0
Total Operating Revenues		677	507	387
Residential | Electric Operations
Operating revenue from contracts with customers		1,375	1,211	1,127
Residential | Gas Distribution
Operating revenue from contracts with customers		303	245	201
Commercial | Electric Operations
Operating revenue from contracts with customers		968	834	746
Commercial | Gas Distribution
Operating revenue from contracts with customers		184	133	103
Industrial | Electric Operations
Operating revenue from contracts with customers		533	424	341
Industrial | Gas Distribution
Operating revenue from contracts with customers		166	103	65
Other | Electric Operations
Operating revenue from contracts with customers		203	157	123
Other | Gas Distribution
Operating revenue from contracts with customers		$ 23	$ 25	$ 18

[1] See Note 16 for amounts attributable to affiliates.