| **Goodwill (Details) (USD $)In Thousands, unless otherwise specified** | 3 Months Ended |
|------------------------------------------------------------------------|----------------|
||
| **Goodwill [Line Items]**                                              |           |
| Balance at December 31, 2013                                           | $ 28,223       |
| Reclassifications to utility plant acquisition adjustment              | (202)          |
| Other                                                                  | (22)           |
| Balance at March 31, 2014                                              | 27,999         |
| Regulated Segment [Member]                                             |           |
| **Goodwill [Line Items]**                                              |           |
| Balance at December 31, 2013                                           | 24,102         |
| Reclassifications to utility plant acquisition adjustment              | (202)          |
| Other                                                                  | (22)           |
| Balance at March 31, 2014                                              | 23,878         |
| Other Segment [Member]                                                 |           |
| **Goodwill [Line Items]**                                              |           |
| Balance at December 31, 2013                                           | 4,121          |
| Reclassifications to utility plant acquisition adjustment              |      |
| Other                                                                  |      |
| Balance at March 31, 2014                                              | $ 4,121        |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266
+ Details**Name:**us-gaap_Goodwill**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                     |
|-------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267
+ Details**Name:**us-gaap_GoodwillOtherChanges**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reclassification Of Goodwill, Acquisition Adjustment
+ References
No definition available.
+ Details**Name:**wtr_ReclassificationOfGoodwillAcquisitionAdjustment**Namespace Prefix:**wtr_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |