| **Taxes Other Than Income Taxes (Details) - USD ($) $ in Thousands** | 3 Months Ended | 9 Months Ended |
|----------------------------------------------------------------------|----------------|----------------|
||
| **Taxes Other Than Income [Line Items]**                             |           |           |   |   |
| Total taxes other than income                                        | $ 14,712       | $ 14,663       | $ 43,094 | $ 43,079 |
| Property [Member]                                                    |           |           |   |   |
| **Taxes Other Than Income [Line Items]**                             |           |           |   |   |
| Total taxes other than income                                        | 7,007          | 6,945          | 20,119 | 20,776 |
| Capital Stock [Member]                                               |           |           |   |   |
| **Taxes Other Than Income [Line Items]**                             |           |           |   |   |
| Total taxes other than income                                        | 430            | 538            | 1,287 | 1,619 |
| Gross Receipts, Excise And Franchise [Member]                        |           |           |   |   |
| **Taxes Other Than Income [Line Items]**                             |           |           |   |   |
| Total taxes other than income                                        | 2,979          | 2,859          | 8,181 | 7,855 |
| Payroll [Member]                                                     |           |           |   |   |
| **Taxes Other Than Income [Line Items]**                             |           |           |   |   |
| Total taxes other than income                                        | 2,140          | 2,072          | 7,775 | 7,425 |
| Regulatory Assessments [Member]                                      |           |           |   |   |
| **Taxes Other Than Income [Line Items]**                             |           |           |   |   |
| Total taxes other than income                                        | 639            | 693            | 1,991 | 2,033 |
| Other [Member]                                                       |           |           |   |   |
| **Taxes Other Than Income [Line Items]**                             |           |           |   |   |
| Total taxes other than income                                        | $ 1,517        | $ 1,556        | $ 3,741 | $ 3,371 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of operating expense for taxes other than income taxes of regulated operation.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688
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| X                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Taxes Other Than Income [Line Items]
+ References
No definition available.
+ Details**Name:**wtr_TaxesOtherThanIncomeLineItems**Namespace Prefix:**wtr_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
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| X                                                                                                                                            |
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| X                                                                                                                                       |
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| X                                                                                                                                                     |
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| X                                                                                                                                          |
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