| **Revenue Recognition (Details) - USD ($) $ in Millions** | 3 Months Ended | 6 Months Ended |
|-----------------------------------------------------------|----------------|----------------|
||
| **Disaggregation of Revenue [Line Items]**                |           |           |   |   |
| Subtotal                                                  | $ 639          | $ 569          | $ 1,389 | $ 1,216 |
| Alternative revenue programs, net of amortization         | (3)            | 2              | (14) | 5 |
| Other Cost of Operating Revenue                           | 4              |           |   |   |
| Other accrued (deferred) revenues, net                    |           | (4)            | (5) | (3) |
| Total retail revenues                                     | 640            | 567            | 1,380 | 1,218 |
| Wholesale revenues                                        | 99             | 62             | 275 | 150 |
| Other operating revenue                                   | 19             | 19             | 32 | 28 |
| Total revenues                                            | 758            | 648            | 1,687 | 1,396 |
| Gain on Derivative Instruments, Pretax                    | 32             | 22             | 120 | 56 |
| Residential [Member]                                      |           |           |   |   |
| **Disaggregation of Revenue [Line Items]**                |           |           |   |   |
| Subtotal                                                  | 307            | 279            | 722 | 641 |
| Commercial [Member]                                       |           |           |   |   |
| **Disaggregation of Revenue [Line Items]**                |           |           |   |   |
| Subtotal                                                  | 219            | 196            | 446 | 393 |
| Industrial [Member]                                       |           |           |   |   |
| **Disaggregation of Revenue [Line Items]**                |           |           |   |   |
| Subtotal                                                  | 104            | 87             | 206 | 169 |
| Direct Access customers [Member]                          |           |           |   |   |
| **Disaggregation of Revenue [Line Items]**                |           |           |   |   |
| Subtotal                                                  | $ 9            | $ 7            | $ 15 | $ 13 |

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| - Definition
Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from change in estimate of transaction price which (increases) decreases obligation to transfer good or service to customer for which consideration from customer has been received or is due. Includes, but is not limited to, change in assessment of whether estimate of variable consideration is constrained.
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| - Definition
Amount of revenue recognized that was previously reported as deferred or unearned revenue.
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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
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| - Definition
Aggregate gain on all derivative instruments recognized in earnings during the period, before tax effects.
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| - Definition
Other costs incurred during the reporting period related to other revenue generating activities.
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The total amount of operating revenues recognized during the period.
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| - Definition
Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).
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The amount of unregulated operating revenues recognized during the period.
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