| **Stock-Based Compensation (Summary Of Compensation Costs) (Details) - USD ($) $ in Thousands** | 3 Months Ended |
|-------------------------------------------------------------------------------------------------|----------------|
||
| Stock Options [Member]                                                                          |           |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**              |           |   |
| Stock-based compensation within operations and maintenance expenses                             | $ 328          | $ 94 |
| Income tax benefit                                                                              | 92             | 58 |
| Performance Share Units [Member]                                                                |           |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**              |           |   |
| Stock-based compensation within operations and maintenance expenses                             | 997            | 859 |
| Income tax benefit                                                                              | 227            | 241 |
| Restricted Stock Units [Member]                                                                 |           |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**              |           |   |
| Stock-based compensation within operations and maintenance expenses                             | 425            | 351 |
| Income tax benefit                                                                              | 120            | 100 |
| Stock Awards [Member]                                                                           |           |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**              |           |   |
| Stock-based compensation within operations and maintenance expenses                             | 180            | 140 |
| Income tax benefit                                                                              | $ 52           | $ 40 |

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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
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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.
+ References
No definition available.
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| X                                                                                                                                             |
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| X                                                                                                                                                   |
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| X                                                                                                                                                 |
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