| **Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Thousands** | 12 Months Ended |
|----------------------------------------------------------------------------------|-----------------|
||
| **Commitments And Contingencies [Line Items]**                                   |            |   |
| Operating lease adjustment period                                                | 5 years         |   |
| Annual lease payments for land                                                   | $ 664           |   |
| Annual lease payments for land due on aggregate remaining years                  | 16,033          |   |
| Estimated annual commitments to purchase water through the next five years       | 4,824           |   |
| Aggregate amount of the commitments for the remaining years                      | $ 8,072         |   |
| Purchase Obligation Term                                                         | 20 years        |   |
| Aggregate amount accrued for loss contingencies                                  | $ 17,681        |   |
| Amount probable of recovery through insurance                                    | 6,108           |   |
| Contingent liability for self-insured employee medical benefit program           | $ 1,515         | $ 1,451 |
| Minimum [Member]                                                                 |            |   |
| **Commitments And Contingencies [Line Items]**                                   |            |   |
| Operating leases, expiration year                                                | 2020            |   |
| Maximum [Member]                                                                 |            |   |
| **Commitments And Contingencies [Line Items]**                                   |            |   |
| Operating leases, expiration year                                                | 2095            |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount as of the balance sheet date of amounts expected to be recovered under the terms of insurance contracts.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.
+ References
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=115931803&loc=d3e12021-110248
+ Details**Name:**us-gaap_LossContingencyEstimateOfPossibleLoss**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This element represents the payments that the lessee is obligated to make or can be required to make in connection with a property under the terms of an agreement classified as an operating lease, excluding contingent rentals and a guarantee by the lessee of the lessor's debt and the lessee's obligation to pay (apart from the rental payments) executory costs such as insurance, maintenance, and taxes.
+ References
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 10 -Section 25 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=77910348&loc=d3e34039-112682Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 10 -Section 55 -Paragraph 40 -Subparagraph (Note 3) -URI http://asc.fasb.org/extlink&oid=82846649&loc=d3e38371-112697
+ Details**Name:**us-gaap_OperatingLeasesRentExpenseMinimumRentals**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Annual lease payments for land due on aggregate remaining years.
+ References
No definition available.
+ Details**Name:**wtr_AnnualLeasePaymentsForLandDueOnAggregateRemainingYears**Namespace Prefix:**wtr_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Commitments And Contingencies [Line Items]
+ References
No definition available.
+ Details**Name:**wtr_CommitmentsAndContingenciesLineItems**Namespace Prefix:**wtr_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                         |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Contingent liability for self-insured employee medical benefit program
+ References
No definition available.
+ Details**Name:**wtr_ContingentLiabilityForSelfInsuredEmployeeMedicalBenefitProgram**Namespace Prefix:**wtr_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Estimated Annual Commitments To Purchase Water Through The Next Five Years
+ References
No definition available.
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| X                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Lease Expiration Year
+ References
No definition available.
+ Details**Name:**wtr_LeaseExpirationYear**Namespace Prefix:**wtr_**Data Type:**xbrli:gYearItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Aggregate long term water purchase commitment, remaining years.
+ References
No definition available.
+ Details**Name:**wtr_LongTermPurchaseAggregateCommitmentRemainingYears**Namespace Prefix:**wtr_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**duration |
| X                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Operating Lease Adjustment Period
+ References
No definition available.
+ Details**Name:**wtr_OperatingLeaseAdjustmentPeriod**Namespace Prefix:**wtr_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Purchase Obligation Term
+ References
No definition available.
+ Details**Name:**wtr_PurchaseObligationTerm**Namespace Prefix:**wtr_**Data Type:**xbrli:durationItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------|
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