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Capitalization (Narrative) (Details) - USD ($) | 1 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Feb. 28, 2015 | Dec. 31, 2014 | May. 31, 2014 | Aug. 31, 2013 | May. 31, 2013 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Oct. 31, 2015 | Jul. 31, 2015 | May. 31, 2015
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares authorized |  | 40,000,000 |  |  |  | 40,000,000 | 40,000,000 |  |  |  |
Authorized shares under plan |  |  |  |  |  | 300,000 |  |  |  |  |
Issuance of shares under the DRP |  |  |  |  |  | $ 1,462,000 | $ 1,493,000 | $ 1,653,000 |  |  |
Additional Shares Authorized By SEC To Be Issued |  |  |  |  |  |  |  |  |  | 700,000 |
Maximum number of shares authorized for grant |  |  |  |  |  | 100,000 |  |  |  |  |
Preferred Stock, Shares Authorized |  | 126,000 |  |  |  | 126,000 | 126,000 |  |  |  |
Preferred Stock, Shares Outstanding |  | 24,000 |  |  |  | 24,000 | 24,000 |  |  |  |
Proceeds from long-term debt borrowing |  |  |  |  |  | $ 7,000,000 | $ 12,246,000 | 4,045,000 |  |  |
Long-term debt |  | $ 140,029,000 |  |  |  | $ 140,279,000 | $ 140,029,000 |  |  |  |
Weighted average interest rate |  | 3.99% |  |  |  | 3.87% | 3.99% |  |  |  |
Deobligated principal payments |  |  |  |  |  | $ 466,000 |  | $ 64,000 |  |  |
Other long term debt |  | $ 50,800,000 |  |  |  | 54,700,000 | $ 50,800,000 |  |  |  |
Customer advances |  | 21,978,000 |  |  |  | $ 20,461,000 | $ 21,978,000 |  |  |  |
Dividend Reinvestment and Common Stock Purchase Plan [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares authorized |  |  |  |  |  | 3,000,000 |  |  |  |  |
Dividend Reinvestment & Common Stock Purchase Plan, cumulative shares |  |  |  |  |  | 2,300,000 |  |  |  |  |
Outside Director Stock Compensation Plan [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Authorized shares under plan |  |  |  |  |  | 72,120 |  |  |  |  |
Common stock granted and issued under plan |  |  |  |  |  | 4,795 | 5,082 | 5,432 |  |  |
Maximum number of shares authorized for grant |  |  |  |  |  | 100,000 |  |  |  |  |
Preferred stock dividends in arrears |  |  |  |  |  | $ 0 |  |  |  |  |
Convertible Preferred Stock $7.00 Series [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares issued upon conversion |  |  |  |  |  | 12 |  |  |  |  |
Convertible preferred stock converted, shares |  |  |  |  |  | 4,293 |  |  |  |  |
Convertible preferred stock converted, value |  |  |  |  |  | $ 500,000 |  |  |  |  |
Stock issued upon conversion of convertible preferred stock (shares) |  |  |  |  |  | 51,516 |  |  |  |  |
Percentage of stock that may be redeemed in a given calander year |  |  |  |  |  | 10.00% |  |  |  |  |
Convertible Preferred Stock $8.00 Series [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares issued upon conversion |  |  |  |  |  | 13.714 |  |  |  |  |
Convertible preferred stock converted, shares |  |  |  | 4,000 |  |  |  |  |  |  |
Convertible preferred stock converted, value |  |  |  | $ 500,000 |  |  |  |  |  |  |
Stock issued upon conversion of convertible preferred stock (shares) |  |  |  | 54,856 |  |  |  |  |  |  |
Tidewater [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loan amount | $ 4,000,000 |  |  |  |  |  |  |  | $ 15,000,000 |  |
Proceeds from long-term debt borrowing | 7,000,000 | 8,000,000 |  |  |  |  |  |  |  |  |
Long-term debt | $ 11,000,000 |  |  |  |  |  |  |  |  |  |
Interest reate | 4.45% |  |  |  |  |  |  |  |  |  |
Maturity date |  |  |  |  |  | Apr. 01, 2040 |  |  |  |  |
New Jersey Environmental Infrastructure Trust [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from long-term debt borrowing |  |  | $ 3,800,000 |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  | $ 30,200,000 |  |  |  |  |
Deobligated principal payments |  |  |  |  |  | 500,000 |  | $ 100,000 |  |  |
First Mortgage Bonds - Series TT [Member] | New Jersey Environmental Infrastructure Trust [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Interest reate |  |  |  |  | 0.00% |  |  |  |  |  |
Maturity date |  |  |  |  | Aug. 01, 2032 |  |  |  |  |  |
First Mortgage Bonds - Series UU [Member] | New Jersey Environmental Infrastructure Trust [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Maturity date |  |  |  |  | Aug. 01, 2032 |  |  |  |  |  |
First Mortgage Bonds - Series VV [Member] | New Jersey Environmental Infrastructure Trust [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of series bonds |  |  | $ 2,800,000 |  |  |  |  |  |  |  |
Interest reate |  |  |  |  |  |  |  |  |  |  | 0.00%
Maturity date |  |  | Aug. 01, 2033 |  |  |  |  |  |  |  |
First Mortgage Bonds - Series WW [Member] | New Jersey Environmental Infrastructure Trust [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Issuance of series bonds |  |  | $ 900,000 |  |  |  |  |  |  |  |
Interest rate, minimum |  |  | 3.00% |  |  |  |  |  |  |  |
Interest rate, maximum |  |  | 5.00% |  |  |  |  |  |  |  |
Maturity date |  |  | Aug. 01, 2033 |  |  |  |  |  |  |  |
Delaware State Revolving Fund [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  | $ 9,300,000 |  |  |  |  |
Delaware State Revolving Fund [Member] | Tidewater [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from long-term debt borrowing |  |  |  |  |  |  | $ 600,000 |  |  |  |
Long-term debt |  | $ 1,100,000 |  |  |  |  | $ 1,100,000 |  |  |  |
Interest reate |  | 3.45% |  |  |  |  | 3.45% |  |  |  |
Maturity date |  |  |  |  |  | Aug. 01, 2031 |  |  |  |  |
New Jersey Economic Development Authority [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  |  | $ 55,400,000 |  |  |  |  |

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