Revenues (Details) - Regulated Electric - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2025		Jun. 30, 2024	Jun. 30, 2025		Jun. 30, 2024
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 498		$ 416	$ 1,013		$ 835
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	508		458	1,029		886
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	396		315	809		627
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	95		83	209		169
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	289	[1]	219	577	[2]	436	[2]
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12		13	23		22
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	23		30	48		66
Transmission
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	78		70	154		141
Alternative and Other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	10		42	16		51
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 1		$ 1	$ 2		$ 1

[1] For the three months ended June 30, 2025, revenues from one C&I customer represented approximately 10.1% of total revenues.

[2] For the six months ended June 30, 2025 and 2024, revenues from one C&I customer represented approximately 9.7% and 10.2% of total revenues, respectively.