Revenues (Details) - Regulated Electric - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Retail
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	$ 1,255	$ 1,137	$ 1,193
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	375	359	352
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	842	739	800
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	38	39	41
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	873	345	361
Transmission
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	287	279	240
Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	6	4	3
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	2,421	1,765	1,797
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	44	105	29
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 2,465	$ 1,870	$ 1,826