| **Accounts Receivable (Narrative) (Details)**                 | Dec. 31, 2014                                                                                                |
|---------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------|
| Pennsylvania [Member]                                         |                                                                                                         |
| utility customers by geographic operating segment, percentage | 47.00%wtr_UtilityCustomersByGeographicOperatingSegmentPercentage/ us-gaap_StatementGeographicalAxis= stpr_PA |
| Ohio [Member]                                                 |                                                                                                         |
| utility customers by geographic operating segment, percentage | 16.00%wtr_UtilityCustomersByGeographicOperatingSegmentPercentage/ us-gaap_StatementGeographicalAxis= stpr_OH |
| North Carolina [Member]                                       |                                                                                                         |
| utility customers by geographic operating segment, percentage | 10.00%wtr_UtilityCustomersByGeographicOperatingSegmentPercentage/ us-gaap_StatementGeographicalAxis= stpr_NC |
| Texas [Member]                                                |                                                                                                         |
| utility customers by geographic operating segment, percentage | 8.00%wtr_UtilityCustomersByGeographicOperatingSegmentPercentage/ us-gaap_StatementGeographicalAxis= stpr_TX  |
| Illinois [Member]                                             |                                                                                                         |
| utility customers by geographic operating segment, percentage | 7.00%wtr_UtilityCustomersByGeographicOperatingSegmentPercentage/ us-gaap_StatementGeographicalAxis= stpr_IL  |

| X                                                                                                                                                                                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Utility Customers By Geographic Operating Segment, Percentage
+ References
No definition available.
+ Details**Name:**wtr_UtilityCustomersByGeographicOperatingSegmentPercentage**Namespace Prefix:**wtr_**Data Type:**num:percentItemType**Balance Type:**na**Period Type:**instant |
| X                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=stpr_IL**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=stpr_NC**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=stpr_OH**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=stpr_PA**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_StatementGeographicalAxis=stpr_TX**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |