| **Intangible Assets and Goodwill (Rollforward) (Details) (USD $)In Thousands, unless otherwise specified** | 12 Months Ended |          | 12 Months Ended |
|------------------------------------------------------------------------------------------------------------|-----------------|----------|-----------------|
||
| **Goodwill [Roll Forward]**                                                                                |            |     |            |   |   |   |
| Goodwill beginning balance                                                                                 | $ 77,294        | $ 74,883 |            |   | $ 140,081 |   |
| Contingent consideration to former shareholders of United Utilities, Inc.                                  |            | 2,411    |            |   |   |   |
| Goodwill acquired during period                                                                            |            |     |            | 140,080 |   | 1,667 |
| Goodwill ending balance                                                                                    | 219,041         | 77,294   | 74,883          |   | 140,081 |   |
| **Finite-lived Intangible Assets [Roll Forward]**                                                          |            |     |            |   |   |   |
| Beginning Balance                                                                                          | 16,560          | 15,835   |            |   |   |   |
| Asset additions                                                                                            | 61,919          | 5,952    |            |   |   |   |
| Amortization expense                                                                                       | 7,044           | 5,227    | 6,039           |   |   |   |
| Ending Balance                                                                                             | $ 71,435        | $ 16,560 | $ 15,835        |   |   |   |

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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.
+ References
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, resulting from a business combination.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.
+ References
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| - Definition
Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
+ References
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| - Definition
Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.
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| - Definition
Amount of other (increase) decrease of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
+ References
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