| **Net Income Per Common Share And Equity Per Common Share (Narrative) (Details) - $ / shares** | 12 Months Ended |
|------------------------------------------------------------------------------------------------|-----------------|
||
| **Net Income Per Common Share and Equity per Commn Share [Abstract]**                          |            |   |
| Employee stock options excluded from calculations of diluted net income per share              | 8,596           |   |
| Equity per common share                                                                        | $ 11.28         | $ 11.02 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
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| - Definition
Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.
+ References
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257
+ Details**Name:**us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount**Namespace Prefix:**us-gaap_**Data Type:**xbrli:sharesItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                  |
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| - References
No definition available.
+ Details**Name:**us-gaap_EarningsPerShareAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                           |
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| - Definition
Equity Per Common Share
+ References
No definition available.
+ Details**Name:**wtr_EquityPerCommonShare**Namespace Prefix:**wtr_**Data Type:**num:perShareItemType**Balance Type:**na**Period Type:**duration |