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Capitalization (Narrative) (Details) - USD ($) $ in Thousands | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Feb. 29, 2016 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Jul. 31, 2015
Schedule of Capitalization [Line Items] |  |  |  |  |
Shares authorized |  | 40,000,000 | 40,000,000 |  |
Authorized shares under plan |  | 300,000 |  |  |
Issuance of shares under the DRP |  | $ 1,453 | $ 1,462 | $ 1,493 |
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 |  |
Preferred Stock, Shares Outstanding |  | 24,000 | 24,000 |  |
Amount drawn |  | $ 8,585 | $ 7,000 | $ 12,246 |
Long-term debt |  | 142,489 | 140,279 |  |
Deobligated principal payments |  | 476 | 466 |  |
Other long term debt |  | 59,700 | 54,700 |  |
Customer advances |  | $ 20,846 | $ 20,461 |  |
All Long-term Debt [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Weighted average interest rate |  | 3.88% | 3.87% |  |
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 |  |  |
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 |  |  |
Outside Director Stock Compensation Plan [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Authorized shares under plan |  | 68,144 |  |  |
Common stock granted and issued under plan |  | 3,976 | 4,795 | 5,082 |
Maximum number of shares authorized for grant |  | 100,000 |  |  |
Dividend Reinvestment and Common Stock Purchase Plan [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Issuance of Common Stock |  | $ 1,500 | $ 1,500 | $ 1,500 |
Shares authorized |  | 3,000,000 |  |  |
Dividend Reinvestment & Common Stock Purchase Plan, cumulative shares |  | 2,300,000 |  |  |
New Jersey Environmental Infrastructure Trust [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Maximum borrowing amount |  | $ 16,000 |  |  |
Maximum borrowing capacity, construction loan |  | $ 11,800 |  |  |
Percentage of principal with stated interest rate |  | 75.00% |  |  |
Percentage of principal with market interest rate |  | 25.00% |  |  |
Amount drawn |  | $ 7,500 |  |  |
Long-term debt |  | $ 34,800 |  |  |
Interest rate |  | 0.00% |  |  |
Deobligated principal payments |  | $ 500 | 500 |  |
Construction Loan [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Interest rate |  | 0.00% |  |  |
Tidewater [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Loan amount | $ 1,200 |  | 11,000 |  |
Amount drawn | $ 1,100 |  | $ 15,000 |  |
Interest rate | 2.00% |  |  |  |
Maturity date | Feb. 01, 2036 |  | Apr. 30, 2040 |  |
Loan amount initially set up as a market-based variable interest rate transaction |  |  | $ 4,000 |  |
New Jersey Economic Development Authority [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Long-term debt |  | $ 55,400 |  |  |
Delaware State Revolving Fund [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Long-term debt |  | $ 9,700 |  |  |
Maximum [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Interest rate |  |  | 4.47% |  |
Minimum [Member] |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |
Interest rate |  |  | 4.45% |  |

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