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Organization, Summary of Significant Accounting Policies and Recent Developments (Tables) | 12 Months Ended
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Dec. 31, 2015
Organization Summary Of Significant Accounting Policies And Recent Developments [Abstract] |
Range of depreciation rates |
Source of Supply |  |  | 1.15% - 3.44% |  | Transmission and Distribution (T&D): |  |  |  |
Pumping |  |  | 2.87% - 5.39% |  | T&D – Mains |  |  | 1.10% - 3.13% |
Water Treatment |  |  | 1.65% - 7.09% |  | T&D – Services |  |  | 2.12% - 3.16% |
General Plant |  |  | 2.08% - 17.84% |  | T&D – Other |  |  | 1.61% - 4.63% |
Allowance for Funds Used During Construction Rates |
|  | 2015 |  |  | 2014 |  |  | 2013 |
Middlesex |  |  |  |  | 6.72% |  |  |  |  |  |  | 7.03% |  |  |  |  |  |  | 7.34% |  |
Tidewater |  |  |  |  | 7.92% |  |  |  |  |  |  | 7.91% |  |  |  |  |  |  | 7.91% |  |

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