| **Property, Plant And Equipment (Details) - USD ($) $ in Thousands**                                 | 12 Months Ended |             |
|------------------------------------------------------------------------------------------------------|-----------------|-------------|
||
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Utility plant and equipment                                                                          | $ 7,404,399     | $ 6,826,043 |
| Net utility plant acquisition adjustment                                                             | 20,832          |        |
| Total property, plant and equipment                                                                  | 7,648,469       | 7,003,993   |
| Mains And Accessories [Member]                                                                       |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Utility plant and equipment                                                                          | 3,344,910       | 3,134,900   |
| Services, Hydrants, Treatment Plants And Reservoirs [Member]                                         |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Utility plant and equipment                                                                          | 1,984,164       | 1,753,433   |
| Operations Structures And Water Tanks [Member]                                                       |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Utility plant and equipment                                                                          | 313,531         | 296,736     |
| Miscellaneous Pumping And Purification Equipment [Member]                                            |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Utility plant and equipment                                                                          | 847,279         | 768,962     |
| Meters, Data Processing, Transportation And Operating Equipment [Member]                             |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Utility plant and equipment                                                                          | 806,978         | 768,655     |
| Land And Other Non-Depreciable Assets [Member]                                                       |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Utility plant and equipment                                                                          | 107,537         | 103,357     |
| Utility Construction Work In progress [Member]                                                       |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Utility construction work in progress                                                                | 235,979         | 201,902     |
| Net Utility Plant Acquisition Adjustment [Member]                                                    |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Net utility plant acquisition adjustment                                                             | (20,832)        | (24,550)    |
| Non-Utility Plant And Equipment [Member]                                                             |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Non-utility plant and equipment                                                                      | $ 28,923        | $ 598       |
| Minimum [Member] | Mains And Accessories [Member]                                                    |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 33 years        |        |
| Minimum [Member] | Services, Hydrants, Treatment Plants And Reservoirs [Member]                      |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 5 years         |        |
| Minimum [Member] | Operations Structures And Water Tanks [Member]                                    |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 14 years        |        |
| Minimum [Member] | Miscellaneous Pumping And Purification Equipment [Member]                         |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 9 years         |        |
| Minimum [Member] | Meters, Data Processing, Transportation And Operating Equipment [Member]          |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 5 years         |        |
| Minimum [Member] | Net Utility Plant Acquisition Adjustment [Member]                                 |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 2 years         |        |
| Minimum [Member] | Non-Utility Plant And Equipment [Member]                                          |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 2 years         |        |
| Maximum [Member] | Mains And Accessories [Member]                                                    |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 93 years        |        |
| Maximum [Member] | Services, Hydrants, Treatment Plants And Reservoirs [Member]                      |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 89 years        |        |
| Maximum [Member] | Operations Structures And Water Tanks [Member]                                    |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 85 years        |        |
| Maximum [Member] | Miscellaneous Pumping And Purification Equipment [Member]                         |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 76 years        |        |
| Maximum [Member] | Meters, Data Processing, Transportation And Operating Equipment [Member]          |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 84 years        |        |
| Maximum [Member] | Net Utility Plant Acquisition Adjustment [Member]                                 |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 59 years        |        |
| Maximum [Member] | Non-Utility Plant And Equipment [Member]                                          |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 50 years        |        |
| Weighted Average [Member] | Mains And Accessories [Member]                                           |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 82 years        |        |
| Weighted Average [Member] | Services, Hydrants, Treatment Plants And Reservoirs [Member]             |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 54 years        |        |
| Weighted Average [Member] | Operations Structures And Water Tanks [Member]                           |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 47 years        |        |
| Weighted Average [Member] | Miscellaneous Pumping And Purification Equipment [Member]                |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 39 years        |        |
| Weighted Average [Member] | Meters, Data Processing, Transportation And Operating Equipment [Member] |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 26 years        |        |
| Weighted Average [Member] | Net Utility Plant Acquisition Adjustment [Member]                        |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 30 years        |        |
| Weighted Average [Member] | Non-Utility Plant And Equipment [Member]                                 |            |        |
| **Property, Plant and Equipment [Line Items]**                                                       |            |        |
| Useful Lives                                                                                         | 49 years        |        |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.
+ References
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.13) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682
+ Details**Name:**us-gaap_PropertyPlantAndEquipmentGross**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| 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.
+ Details**Name:**us-gaap_PropertyPlantAndEquipmentLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.
+ References
No definition available.
+ Details**Name:**us-gaap_PropertyPlantAndEquipmentUsefulLife**Namespace Prefix:**us-gaap_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of acquisition adjustments included in property, plant and equipment (PPE) for utilities.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAmountOfAcquisitionAdjustments1**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Period end amount of construction work in progress in public utility.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                           |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Period end book value of equipment owned (but not classified elsewhere) by the public utility.
+ References
No definition available.
+ Details**Name:**us-gaap_PublicUtilitiesPropertyPlantAndEquipmentEquipment**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Non-utility plant and equipment
+ References
No definition available.
+ Details**Name:**wtr_NonUtilityPlantAndEquipment**Namespace Prefix:**wtr_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LandMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_PropertyPlantAndEquipmentByTypeAxis=wtr_NonUtilityPlantAndEquipmentMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**srt_RangeAxis=srt_MinimumMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------|
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