| **Regulatory Assets And Liabilities (Narrative) (Details) - USD ($) $ in Thousands** |          | 1 Months Ended | 12 Months Ended |
|--------------------------------------------------------------------------------------|----------|----------------|-----------------|
||
| **Regulatory Assets And Liabilities [Line Items]**                                   |     |           |            |   |   |
| Amortization of deferred repair tax adjustment                                       |     |           | $ 38,000        |   |   |
| Amortization period                                                                  |     |           | 10 years        |   |   |
| Increase in net income                                                               |     |           | $ 16,274        | $ 16,734 | $ 16,734 |
| Statutory federal tax rate                                                           |     |           | 21.00%          | 35.00% | 35.00% |
| Redemption of debt                                                                   |     | $ 313,500      | $ 1,048,471     | $ 914,125 | $ 359,068 |
| Make whole payment                                                                   | $ 25,237 | $ 25,237       | $ 25,237        |   |   |
| Scenario, Plan [Member]                                                              |     |           |            |   |   |
| **Regulatory Assets And Liabilities [Line Items]**                                   |     |           |            |   |   |
| Statutory federal tax rate                                                           |     |           | 21.00%          |   |   |
| Minimum [Member]                                                                     |     |           |            |   |   |
| **Regulatory Assets And Liabilities [Line Items]**                                   |     |           |            |   |   |
| Water tank painting costs amortization period                                        |     |           | 7 years         |   |   |
| Maturity date                                                                        |     |           | 2022            |   |   |
| Rate case filing expense amortization period                                         |     |           | 1 year          |   |   |
| Maturity                                                                             |     | 2019           |            |   |   |
| Redemption percentage                                                                | 3.57%    | 3.57%          |            |   |   |
| Maximum [Member]                                                                     |     |           |            |   |   |
| **Regulatory Assets And Liabilities [Line Items]**                                   |     |           |            |   |   |
| Water tank painting costs amortization period                                        |     |           | 10 years        |   |   |
| Maturity date                                                                        |     |           | 2029            |   |   |
| Rate case filing expense amortization period                                         |     |           | 5 years         |   |   |
| Maturity                                                                             |     | 2037           |            |   |   |
| Redemption percentage                                                                | 5.83%    | 5.83%          |            |   |   |
| Postretirement Benefits [Member]                                                     |     |           |            |   |   |
| **Regulatory Assets And Liabilities [Line Items]**                                   |     |           |            |   |   |
| Regulatory asset recovery period                                                     |     |           | 10 years        |   |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Percentage of domestic federal statutory tax rate applicable to pretax income (loss).
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.
+ References
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| X                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amortizataion period of rate case filing expense
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amortization of deferred repair tax adjustment
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amortization Of Deferred Repair Tax Adjustment Impact On Net Income Loss
+ References
No definition available.
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| X                                                                                                                                                                                                                                                   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Debt Instrument, Maturity Date, Year
+ References
No definition available.
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| X                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Debt Instrument, Maturity Year
+ References
No definition available.
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| X                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Regulatory Asset Recovery Period
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Regulatory Assets And Liabilities [Line Items]
+ References
No definition available.
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| X                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tax Adjustment, Amortization Period
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Water tank painting costs amortized over a period.
+ References
No definition available.
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| X                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                            |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------|
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