| **Segment Information (Company's Segment Information, Assets) (Details) - USD ($) $ in Thousands** | Mar. 31, 2020 | Dec. 31, 2019 |
|----------------------------------------------------------------------------------------------------|---------------|---------------|
| **Segment Reporting Information [Line Items]**                                                     |          |          |
| Total assets                                                                                       | $ 12,928,986  | $ 9,361,985   |
| Other [Member]                                                                                     |          |          |
| **Segment Reporting Information [Line Items]**                                                     |          |          |
| Total assets                                                                                       | 204,372       | 2,092,581     |
| Regulated [Member] | Water [Member]                                                                |          |          |
| **Segment Reporting Information [Line Items]**                                                     |          |          |
| Total assets                                                                                       | 7,362,550     | $ 7,269,404   |
| Regulated [Member] | Natural Gas [Member]                                                          |          |          |
| **Segment Reporting Information [Line Items]**                                                     |          |          |
| Total assets                                                                                       | $ 5,362,064   |          |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.
+ References
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| 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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| X                                                                                                                                                             |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                  |
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| X                                                                                                                                              |
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| X                                                                                                                                                   |
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