Revenues (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2022 | Sep. 30, 2021 |
Total revenues | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Total revenues | $ 294 | $ 274 | $ 900 | $ 810 |
Regulated Electric | Total revenues | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Total revenues | 274 | 252 | 767 | 700 |
Regulated Natural Gas | Total revenues | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Total revenues | 20 | 22 | 133 | 110 |
Retail | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 237 | 221 | 733 | 656 |
Retail | Residential | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 87 | 81 | 295 | 262 |
Retail | C&I | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 148 | 138 | 432 | 387 |
Retail | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 2 | 2 | 6 | 7 |
Retail | Regulated Electric | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 219 | 201 | 606 | 551 |
Retail | Regulated Electric | Residential | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 78 | 73 | 226 | 208 |
Retail | Regulated Electric | C&I | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 139 | 126 | 374 | 336 |
Retail | Regulated Electric | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 2 | 2 | 6 | 7 |
Retail | Regulated Natural Gas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 18 | 20 | 127 | 105 |
Retail | Regulated Natural Gas | Residential | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 9 | 8 | 69 | 54 |
Retail | Regulated Natural Gas | C&I | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 9 | 12 | 58 | 51 |
Retail | Regulated Natural Gas | Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 0 | 0 | 0 | 0 |
Interchange | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 51 | 48 | 150 | 140 |
Interchange | Regulated Electric | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 51 | 48 | 150 | 140 |
Interchange | Regulated Natural Gas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 0 | 0 | 0 | 0 |
Other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 2 | 2 | 6 | 4 |
Other | Regulated Electric | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 1 | 0 | 3 | 0 |
Other | Regulated Natural Gas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 1 | 2 | 3 | 4 |
Total revenue from contracts with customers | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 290 | 271 | 889 | 800 |
Total revenue from contracts with customers | Regulated Electric | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 271 | 249 | 759 | 691 |
Total revenue from contracts with customers | Regulated Natural Gas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Revenue from contracts with customers | 19 | 22 | 130 | 109 |
Alternative revenue and other | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Alternative revenue and other | 4 | 3 | 11 | 10 |
Alternative revenue and other | Regulated Electric | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Alternative revenue and other | 3 | 3 | 8 | 9 |
Alternative revenue and other | Regulated Natural Gas | | | | |
Disaggregation of Revenue [Line Items] | | | | |
Alternative revenue and other | $ 1 | $ 0 | $ 3 | $ 1 |