Revenue Recognition (Disaggregation of Revenue) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Total Operating Revenues	[1]	$ 1,083	$ 863	$ 2,841	$ 2,299
Electric Operations
Operating revenue from contracts with customers		936	768	2,357	1,942
Other revenues		8	4	22	12
Total Operating Revenues		944	772	2,379	1,954
Gas Distribution
Operating revenue from contracts with customers		138	91	461	344
Other revenues		1	0	1	1
Total Operating Revenues		139	91	462	345
Residential | Electric Operations
Operating revenue from contracts with customers		433	366	1,065	912
Residential | Gas Distribution
Operating revenue from contracts with customers		39	34	193	170
Commercial | Electric Operations
Operating revenue from contracts with customers		294	244	740	618
Commercial | Gas Distribution
Operating revenue from contracts with customers		41	26	124	91
Industrial | Electric Operations
Operating revenue from contracts with customers		153	112	396	295
Industrial | Gas Distribution
Operating revenue from contracts with customers		54	27	128	67
Other | Electric Operations
Operating revenue from contracts with customers		56	46	156	117
Other | Gas Distribution
Operating revenue from contracts with customers		$ 4	$ 4	$ 16	$ 16

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