Revenues (Details) - 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	$ 4,049	$ 3,547	$ 3,705
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	2,002	1,735	1,767
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	1,998	1,764	1,888
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	49	48	50
Wholesale
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	228	212	166
Transmission
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	75	62	52
Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	203	181	139
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	4,555	4,002	4,062
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	260	181	175
Regulated Electric | Retail
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	2,883	2,633	2,635
Regulated Electric | Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	1,174	1,073	1,006
Regulated Electric | Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	1,660	1,512	1,579
Regulated Electric | Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	49	48	50
Regulated Electric | Wholesale
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	228	212	166
Regulated Electric | Transmission
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	75	62	52
Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	44	56	32
Regulated Electric | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	3,230	2,963	2,885
Regulated Electric | Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	183	153	148
Regulated Natural Gas | Retail
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	1,124	875	1,031
Regulated Natural Gas | Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	816	650	750
Regulated Natural Gas | Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	308	225	281
Regulated Natural Gas | Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	0	0	0
Regulated Natural Gas | Wholesale
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	0	0	0
Regulated Natural Gas | Transmission
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	0	0	0
Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	159	125	107
Regulated Natural Gas | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	1,283	1,000	1,138
Regulated Natural Gas | Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	72	24	23
All Other | Retail
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	42	39	39
All Other | Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	12	12	11
All Other | Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	30	27	28
All Other | Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	0	0	0
All Other | Wholesale
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	0	0	0
All Other | Transmission
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	0	0	0
All Other | Other
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	0	0	0
All Other | Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from Contracts with Customers	42	39	39
All Other | Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	5	4	4
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	4,815	4,183	4,237
Total revenues | Regulated Electric
Disaggregation of Revenue [Line Items]
Total revenues	3,413	3,116	3,033
Total revenues | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues	1,355	1,024	1,161
Total revenues | All Other
Disaggregation of Revenue [Line Items]
Total revenues	$ 47	$ 43	$ 43