| **Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)** | 3 Months Ended                                                                                                                                                                                    | 12 Months Ended               | 1 Months Ended                | 10 Months Ended               | 1 Months Ended                                                                                                                                                                                    |                               |
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| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Percentage of operating revenue from largest operating subsidiary            |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 53.00%wtr_PercentageOfOperatingRevenueFromLargestOperatingSubsidiary |   |   |   |   |   |   |   |   |   |   |   |
| Percentage of net income from largest operating subsidiary                   |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 70.00%wtr_PercentageOfNetIncomeFromLargestOperatingSubsidiary |   |   |   |   |   |   |   |   |   |   |   |
| Number of counties providing operating services                              |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 26wtr_NumberOfCountiesProvidingOperatingServices |   |   |   |   |   |   |   |   |   |   |   |
| Number of operating segments                                                 |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 10us-gaap_NumberOfOperatingSegments |   |   |   |   |   |   |   |   |   |   |   |
| Number of reportable segments                                                |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 1us-gaap_NumberOfReportableSegments |   |   |   |   |   |   |   |   |   |   |   |
| Operating revenues                                                           | $ 191,389,000us-gaap_Revenues                                                                                                                                                                     | $ 210,535,000us-gaap_Revenues | $ 195,307,000us-gaap_Revenues | $ 182,672,000us-gaap_Revenues | $ 187,078,000us-gaap_Revenues                                                                                                                                                                     | $ 202,320,000us-gaap_Revenues | $ 193,943,000us-gaap_Revenues | $ 178,552,000us-gaap_Revenues | $ 779,903,000us-gaap_Revenues | $ 761,893,000us-gaap_Revenues | $ 750,685,000us-gaap_Revenues | $ 680,677,000us-gaap_Revenues | $ 653,812,000us-gaap_Revenues |   |   |   |   |   |   |   |
| Net utility plant acquisition adjustment                                     | 20,164,000us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAmountOfAcquisitionAdjustments1                                                                                                         |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 20,164,000us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAmountOfAcquisitionAdjustments1 |   |   |   |   | 20,164,000us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAmountOfAcquisitionAdjustments1 |   |   |   |   |   |   |
| Amortization of the acquisition adjustments                                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 2,648,000wtr_PublicUtilitiesPropertyPlantAndEquipmentAmortizationOfAcquisitionAdjustments | 2,480,000wtr_PublicUtilitiesPropertyPlantAndEquipmentAmortizationOfAcquisitionAdjustments | 2,698,000wtr_PublicUtilitiesPropertyPlantAndEquipmentAmortizationOfAcquisitionAdjustments |   |   |   |   |   |   |   |   |   |
| utility expenditures expected to be recovered                                | 15,954,000wtr_CapitalizedCostsIncludedInPropertyPlantAndEquipment                                                                                                                                 |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 15,954,000wtr_CapitalizedCostsIncludedInPropertyPlantAndEquipment |   |   |   |   | 15,954,000wtr_CapitalizedCostsIncludedInPropertyPlantAndEquipment |   |   |   |   |   |   |
| Deferred cost reported as a component of net property, plant and equipment   | 21,490,000us-gaap_DeferredCostsCurrentAndNoncurrent                                                                                                                                               |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 21,490,000us-gaap_DeferredCostsCurrentAndNoncurrent |   |   |   |   | 21,490,000us-gaap_DeferredCostsCurrentAndNoncurrent |   |   |   |   |   |   |
| Capital Expenditures Incurred but Not yet Paid                               |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 31,039,000us-gaap_CapitalExpendituresIncurredButNotYetPaid | 30,974,000us-gaap_CapitalExpendituresIncurredButNotYetPaid | 29,588,000us-gaap_CapitalExpendituresIncurredButNotYetPaid |   |   |   |   |   |   |   |   |   |
| Overdraft for certain disbursement cash accounts                             | 21,431,000us-gaap_BankAcceptancesExecutedAndOutstanding                                                                                                                                           |                          |                          |                          | 21,753,000us-gaap_BankAcceptancesExecutedAndOutstanding                                                                                                                                           |                          |   |   | 21,431,000us-gaap_BankAcceptancesExecutedAndOutstanding | 21,753,000us-gaap_BankAcceptancesExecutedAndOutstanding |   |   |   | 21,431,000us-gaap_BankAcceptancesExecutedAndOutstanding |   |   | 21,753,000us-gaap_BankAcceptancesExecutedAndOutstanding |   |   |   |
| Joint venture ownership percentage                                           | 49.00%us-gaap_EquityMethodInvestmentOwnershipPercentage                                                                                                                                           |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 49.00%us-gaap_EquityMethodInvestmentOwnershipPercentage |   |   |   |   | 49.00%us-gaap_EquityMethodInvestmentOwnershipPercentage |   |   |   |   |   |   |
| Joint Venture Distributions                                                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 1,372,000us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital | 1,960,000us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital |   |   |   |   |   |   |   |   |   |   |
| Amortization period of tax repair catch up adjustment                        |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 10wtr_AmortizationPeriodOfTaxRepairCatchUpAdjustment |   |   |   |   |   |   |   |   |   |   |   |
| Non-cash property as advances or contributions                               |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 43,642,000us-gaap_ProceedsFromContributionInAidOfConstruction | 26,188,000us-gaap_ProceedsFromContributionInAidOfConstruction | 27,212,000us-gaap_ProceedsFromContributionInAidOfConstruction |   |   |   |   |   |   |   |   |   |
| Impaired goodwill                                                            |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 0us-gaap_GoodwillImpairmentLoss |   |   |   |   |   |   |   |   |   |   |   |
| Goodwill                                                                     | 31,184,000us-gaap_Goodwill                                                                                                                                                                        |                          |                          |                          | 28,223,000us-gaap_Goodwill                                                                                                                                                                        |                          |   |   | 31,184,000us-gaap_Goodwill | 28,223,000us-gaap_Goodwill | 28,152,000us-gaap_Goodwill |   |   | 31,184,000us-gaap_Goodwill |   |   | 28,223,000us-gaap_Goodwill |   |   | 1,679,000us-gaap_Goodwill |
| Discontinued Operations [Member]                                             |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Goodwill                                                                     |                                                                                                                                                                                              |                          |                          |                          | 0us-gaap_Goodwill/ us-gaap_StatementOperatingActivitiesSegmentAxis= us-gaap_SegmentDiscontinuedOperationsMember                                                                                   |                          |   |   |   | 0us-gaap_Goodwill/ us-gaap_StatementOperatingActivitiesSegmentAxis= us-gaap_SegmentDiscontinuedOperationsMember |   |   |   |   |   |   | 0us-gaap_Goodwill/ us-gaap_StatementOperatingActivitiesSegmentAxis= us-gaap_SegmentDiscontinuedOperationsMember |   |   |   |
| City of Fort Wayne, Indiana [Member] | Discontinued Operations [Member]      |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of customers                                                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   | 13,000 |   |   |   |   |   |   |
| Ohio [Member]                                                                |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of customers                                                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   | 59,000 |   |   |   |   |   |
| Florida [Member]                                                             |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of customers                                                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   | 38,000 |   |   |   |   |
| NumberofSeparateSalesTransactions                                            |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   | five |   |   |   |
| Florida [Member] | Discontinued Operations [Member]                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of customers                                                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   | 38,000 |   |   |   |   |
| New York [Member]                                                            |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of customers                                                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   | 51,000 |   |   |
| New York [Member] | Discontinued Operations [Member]                         |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of customers                                                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   | 51,000 |   |   |   |   |   |
| Maine [Member]                                                               |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of customers                                                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   | 16,000 |   |   |
| Maine [Member] | Discontinued Operations [Member]                            |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of customers                                                          |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   | 16,000 |   |
| Other State [Member]                                                         |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of states providing services in other than Pennsylvania               |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 7wtr_NumberOfStatesProvidingServicesInOtherThanPennsylvania/ us-gaap_StatementGeographicalAxis= wtr_OtherStateMember |   |   |   |   |   |   |   |   |   |   |   |
| Regulated Segment [Member]                                                   |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of operating segments                                                 |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 8us-gaap_NumberOfOperatingSegments/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember |   |   |   |   |   |   |   |   |   |   |   |
| Amount of AFUDC related to equity funds                                      | 3,640,000us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember |                          |                          |                          | 533,000us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember   |                          |   |   | 3,640,000us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember | 533,000us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember | 188,000us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember |   |   | 3,640,000us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember |   |   | 533,000us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember |   |   |   |
| Goodwill                                                                     | 24,564,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember                                                                                                     |                          |                          |                          | 24,102,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember                                                                                                     |                          |   |   | 24,564,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember | 24,102,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember | 24,031,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember |   |   | 24,564,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember |   |   | 24,102,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_RegulatedSegmentMember |   |   |   |
| Other [Member]                                                               |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Operating revenues                                                           |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 23,846,000us-gaap_Revenues/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember | 17,366,000us-gaap_Revenues/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember | 17,730,000us-gaap_Revenues/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember |   |   |   |   |   |   |   |   |   |
| Goodwill                                                                     | 6,620,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember                                                                                                 |                          |                          |                          | 4,121,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember                                                                                                 |                          |   |   | 6,620,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember | 4,121,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember | 4,121,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember |   |   | 6,620,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember |   |   | 4,121,000us-gaap_Goodwill/ us-gaap_StatementBusinessSegmentsAxis= wtr_OtherReportingSegmentMember |   |   |   |
| Not Quantitatively Significant [Member]                                      |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Number of operating segments                                                 |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 2us-gaap_NumberOfOperatingSegments/ us-gaap_StatementBusinessSegmentsAxis= wtr_NotQuantitativelySignificantMember |   |   |   |   |   |   |   |   |   |   |   |
| Non-Regulated Businesses [Member]                                            |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Operating revenues                                                           |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 24,189,000us-gaap_Revenues/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember | 17,712,000us-gaap_Revenues/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember | 18,247,000us-gaap_Revenues/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember |   |   |   |   |   |   |   |   |   |
| Amount of AFUDC related to equity funds                                      | $ 0us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember |                          |                          |                          | $ 0us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember |                          |   |   | $ 0us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember | $ 0us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember | $ 0us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember |   |   | 0us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember |   |   | 0us-gaap_PublicUtilitiesAmountOfAllowanceForFundsUsedDuringConstructionEquityCostsCapitalizedOnlyForRateMakingPurposes/ us-gaap_StatementBusinessSegmentsAxis= wtr_NonRegulatedBusinessesMember |   |   |   |
| Minimum [Member]                                                             |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Amortized Period                                                             |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 2 years |   |   |   |   |   |   |   |   |   |   |   |
| Maximum [Member]                                                             |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| **Summary Of Significant Accounting Policies [Line Items]**                  |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Amortized Period                                                             |                                                                                                                                                                                              |                          |                          |                          |                                                                                                                                                                                              |                          |   |   | 53 years |   |   |   |   |   |   |   |   |   |   |   |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount as of the balance sheet date of drafts and bills of exchange that have been accepted by the reporting bank, or by others for its own account, as its liability to holders of the drafts.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.14) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 14 -Article 9
+ Details**Name:**us-gaap_BankAcceptancesExecutedAndOutstanding**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**credit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Future cash outflow to pay for purchases of fixed assets that have occurred.
+ References
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| - Definition
The carrying amount of deferred costs.
+ References
No definition available.
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| - Definition
The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.
+ References
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| - Definition
Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
+ References
No definition available.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - 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
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of loss from the write-down 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
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.
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No definition available.
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| - Definition
Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.
+ References
No definition available.
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| - Definition
The cash inflow from developers, builders, governmental agencies and municipalities that provide the entity with cash to extend its construction services to their properties.
+ References
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| - Definition
Cash dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporations that are returns of capital. Excludes dividends or distributions from equity method investments classified as operating activities.
+ References
No definition available.
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| - Definition
Amount of costs of debt and equity financing capitalized for setting rates but not capitalized for financial statement purposes.
+ References
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| - Definition
Amount of acquisition adjustments included in property, plant and equipment (PPE) for utilities.
+ References
No definition available.
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| - Definition
Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).
+ References
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| - Definition
Amortization period of tax repair catch up adjustment
+ References
No definition available.
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| - Definition
Capitalized Costs Included In Property Plant And Equipment
+ References
No definition available.
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| - Definition
Number of counties providing operating services to in Pennsylvania other than north and west of Philadelphia.
+ References
No definition available.
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| - Definition
Number of customers.
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| - Definition
The number of separate sales transactions that occurred in 2013 in Florida
+ References
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| - Definition
Number Of States Providing Services In Other Than Pennsylvania
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| - Definition
Percentage of net income from largest operating subsidiary
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| - Definition
Percentage Of Operating Revenue From Largest Operating Subsidiary
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| - Definition
Public Utilities Property Plant And Equipment Amortization Of Acquisition Adjustments
+ References
No definition available.
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