| **Pension Plans And Other Post-Retirement Benefits (Schedule Of Fair Value Of Plan Assets) (Details) - USD ($) $ in Thousands**  | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 |
|----------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|---------------|
| Pension Benefits [Member]                                                                                                        |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | $ 242,360     | $ 238,605     | $ 244,897     |
| Pension Benefits [Member] | Fair Value, Inputs, Level 1 [Member]                                                                 |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 184,213       | 193,478       |          |
| Pension Benefits [Member] | Fair Value, Inputs, Level 2 [Member]                                                                 |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 58,147        | 45,127        |          |
| Pension Benefits [Member] | Common stocks [Member]                                                                               |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 152,740       | 146,970       |          |
| Pension Benefits [Member] | Common stocks [Member] | Fair Value, Inputs, Level 1 [Member]                                        |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 152,740       | 146,970       |          |
| Pension Benefits [Member] | Mutual funds [Member]                                                                                |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 3,668         | 3,605         |          |
| Pension Benefits [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member]                                         |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 3,668         | 3,605         |          |
| Pension Benefits [Member] | International equities [Member]                                                                      |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 13,813        | 14,180        |          |
| Pension Benefits [Member] | International equities [Member] | Fair Value, Inputs, Level 1 [Member]                               |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 13,813        | 14,180        |          |
| Pension Benefits [Member] | US Treasury and government agency bonds [Member]                                                     |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 11,170        | 22,953        |          |
| Pension Benefits [Member] | US Treasury and government agency bonds [Member] | Fair Value, Inputs, Level 2 [Member]              |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 11,170        | 22,953        |          |
| Pension Benefits [Member] | Corporate and foreign bonds [Member]                                                                 |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 24,385        | 13,579        |          |
| Pension Benefits [Member] | Corporate and foreign bonds [Member] | Fair Value, Inputs, Level 2 [Member]                          |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 24,385        | 13,579        |          |
| Pension Benefits [Member] | Mutual funds [Member]                                                                                |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 9,752         | 21,523        |          |
| Pension Benefits [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member]                                         |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 9,752         | 21,523        |          |
| Pension Benefits [Member] | Real estate [Member]                                                                                 |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 2,613         | 5,981         |          |
| Pension Benefits [Member] | Real estate [Member] | Fair Value, Inputs, Level 1 [Member]                                          |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 2,613         | 5,981         |          |
| Pension Benefits [Member] | Commodity funds [Member]                                                                             |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 1,279         | 1,169         |          |
| Pension Benefits [Member] | Commodity funds [Member] | Fair Value, Inputs, Level 1 [Member]                                      |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 1,279         | 1,169         |          |
| Pension Benefits [Member] | Cash And Cash Equivalents [Member]                                                                   |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 22,940        | 8,645         |          |
| Pension Benefits [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]                            |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 348           | 50            |          |
| Pension Benefits [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]                            |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 22,592        | 8,595         |          |
| Other Postretirement Benefits [Member]                                                                                           |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 46,085        | 43,704        | $ 43,326      |
| Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 1 [Member]                                                    |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 25,545        | 27,057        |          |
| Other Postretirement Benefits [Member] | Fair Value, Inputs, Level 2 [Member]                                                    |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 20,540        | 16,647        |          |
| Other Postretirement Benefits [Member] | Common stocks [Member]                                                                  |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 10,667        | 11,772        |          |
| Other Postretirement Benefits [Member] | Common stocks [Member] | Fair Value, Inputs, Level 1 [Member]                           |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 10,667        | 11,772        |          |
| Other Postretirement Benefits [Member] | Mutual funds [Member]                                                                   |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 13,464        | 12,030        |          |
| Other Postretirement Benefits [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member]                            |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 13,464        | 12,030        |          |
| Other Postretirement Benefits [Member] | International equities [Member]                                                         |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 1,242         | 1,078         |          |
| Other Postretirement Benefits [Member] | International equities [Member] | Fair Value, Inputs, Level 1 [Member]                  |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 1,242         | 1,078         |          |
| Other Postretirement Benefits [Member] | US Treasury and government agency bonds [Member]                                        |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 4,968         | 4,551         |          |
| Other Postretirement Benefits [Member] | US Treasury and government agency bonds [Member] | Fair Value, Inputs, Level 2 [Member] |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 4,968         | 4,551         |          |
| Other Postretirement Benefits [Member] | Corporate and foreign bonds [Member]                                                    |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 6,347         | 4,476         |          |
| Other Postretirement Benefits [Member] | Corporate and foreign bonds [Member] | Fair Value, Inputs, Level 2 [Member]             |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 6,347         | 4,476         |          |
| Other Postretirement Benefits [Member] | Mutual funds [Member]                                                                   |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     |          | 2,177         |          |
| Other Postretirement Benefits [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member]                            |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     |          | 2,177         |          |
| Other Postretirement Benefits [Member] | Alternative investments [Member]                                                        |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 172           |          |          |
| Other Postretirement Benefits [Member] | Alternative investments [Member] | Fair Value, Inputs, Level 1 [Member]                 |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 172           |          |          |
| Other Postretirement Benefits [Member] | Cash And Cash Equivalents [Member]                                                      |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | 9,225         | 7,620         |          |
| Other Postretirement Benefits [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]               |          |          |          |
| **Defined Benefit Plan Disclosure [Line Items]**                                                                                 |          |          |          |
| Total assets                                                                                                                     | $ 9,225       | $ 7,620       |          |

| X                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.
+ References
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