Revenue Recognition (Disaggregation of Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Total Operating Revenues	[1]	$ 759	$ 849
Electric Operations
Operating revenue from contracts with customers		576	647
Other revenues		6	8
Total Operating Revenues		582	655
Gas Distribution
Operating revenue from contracts with customers		177	194
Other revenues		0	0
Total Operating Revenues		177	194
Residential | Electric Operations
Operating revenue from contracts with customers		262	300
Residential | Gas Distribution
Operating revenue from contracts with customers		109	109
Commercial | Electric Operations
Operating revenue from contracts with customers		187	201
Commercial | Gas Distribution
Operating revenue from contracts with customers		42	48
Industrial | Electric Operations
Operating revenue from contracts with customers		91	108
Industrial | Gas Distribution
Operating revenue from contracts with customers		22	31
Other | Electric Operations
Operating revenue from contracts with customers		36	38
Other | Gas Distribution
Operating revenue from contracts with customers		$ 4	$ 6

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