| **Stock-Based Compensation (Summary Of Compensation Costs) (Details) (USD $)In Thousands, unless otherwise specified** | 3 Months Ended |
|------------------------------------------------------------------------------------------------------------------------|----------------|
||
| Stock Options [Member]                                                                                                 |           |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**                                     |           |   |
| Stock-based compensation within opertions and maintenance expense                                                      |           | $ 30 |
| Income tax benefit                                                                                                     | 73             | 238 |
| Performance Share Units [Member]                                                                                       |           |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**                                     |           |   |
| Stock-based compensation within opertions and maintenance expense                                                      | 1,002          | 715 |
| Income tax benefit                                                                                                     | 410            | 291 |
| Restricted Stock Units [Member]                                                                                        |           |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**                                     |           |   |
| Stock-based compensation within opertions and maintenance expense                                                      | 236            | 178 |
| Income tax benefit                                                                                                     | 98             | 73 |
| Restricted Stock [Member]                                                                                              |           |   |
| **Share-based Compensation Arrangement by Share-based Payment Award [Line Items]**                                     |           |   |
| Stock-based compensation within opertions and maintenance expense                                                      | 92             | 92 |
| Income tax benefit                                                                                                     | $ 38           | $ 38 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F
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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
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901
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| X                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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