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Capitalization (Narrative) (Details) - USD ($) $ in Thousands | 1 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
May 31, 2018 | Nov. 30, 2017 | Feb. 29, 2016 | Sep. 30, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2018 | Aug. 31, 2018 | Apr. 30, 2018 | Mar. 31, 2018
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 |  |  |  |  | $ 1,150 | $ 1,234 | $ 1,453 |  |  |  |
Additional Shares Authorized By SEC To Be Issued |  |  |  |  | 600,000 |  |  |  |  |  |
Maximum number of shares authorized for grant |  |  |  |  | 50,000 |  |  |  |  |  |
Preferred Stock, Shares Authorized |  |  |  |  | 126,000 | 126,000 |  |  |  |  |
Preferred Stock, Shares Outstanding |  |  |  |  | 23,000 | 23,000 |  |  |  |  |
Amount drawn |  |  |  |  | $ 22,076 | $ 11,523 | 8,585 |  |  |  |
Long-term debt |  |  |  |  | 162,904 | 147,852 |  |  |  |  |
Deobligated principal payments |  |  |  |  |  |  | $ 476 |  |  |  |
Other long term debt |  |  |  |  | 61,500 | 52,500 |  |  |  |  |
Customer advances |  |  |  |  | $ 22,572 | $ 21,423 |  |  |  |  |
All Long-term Debt [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Weighted average interest rate |  |  |  |  | 3.30% | 3.77% |  |  |  |  |
Convertible Preferred Stock $7.00 Series [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Shares issued upon conversion |  |  |  |  | 12 |  |  |  |  |  |
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 |  |  |  |  | 60,164 |  |  |  |  |  |
Common stock granted and issued under plan |  |  |  |  | 4,004 | 3,976 | 3,976 |  |  |  |
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 |  |  |  |  | $ 1,200 | $ 1,200 | $ 1,500 |  |  |  |
Shares authorized |  |  |  |  | 3,000,000 |  |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Common stock granted and issued under plan |  |  |  |  | 200,000 |  |  |  |  |  |
Percentage of offering shares on discount to participants |  |  |  |  | 5.00% |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing amount |  |  |  |  |  |  |  |  |  |  | $ 14,000
Maximum borrowing capacity, construction loan |  |  |  |  | $ 9,500 |  |  | $ 8,700 | $ 43,500 | $ 55,000 |
Percentage of principal with stated interest rate |  |  |  |  | 75.00% |  |  |  |  |  |
Percentage of principal with market interest rate |  |  |  |  | 25.00% |  |  |  |  |  |
Amount drawn |  |  |  |  | $ 9,300 |  |  |  |  |  |
Long-term debt |  |  |  |  | $ 62,500 |  |  |  |  |  |
Interest rate |  |  |  |  | 0.00% |  |  |  |  |  |
Deobligated principal payments |  |  |  |  | $ 500 |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] | Minimum [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of first mortgage bond |  |  |  | $ 25,000 |  |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] | Maximum [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of first mortgage bond |  |  |  | $ 75,000 |  |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] | Series XX [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity, construction loan |  | $ 11,300 |  |  |  |  |  |  |  |  |
Percentage of principal with bond interest rate |  | 0.00% |  |  |  |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] | Series YY [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity, construction loan |  | $ 3,900 |  |  |  |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] | Series YY [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percentage of principal with bond interest rate |  | 3.00% |  |  |  |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] | Series YY [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percentage of principal with bond interest rate |  | 5.00% |  |  |  |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Amount drawn |  |  |  |  | $ 15,100 |  |  |  |  |  |
Maturity date |  |  |  |  | Aug. 01, 2047 |  |  |  |  |  |
Construction Loan [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Interest rate |  |  |  |  | 0.00% |  |  |  |  |  |
New Jersey Economic Development Authority [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of first mortgage bond |  |  |  |  | $ 140,000 |  |  |  |  |  |
Maturity date |  |  |  |  | Dec. 31, 2022 |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Amount drawn |  |  |  |  | $ 10,500 |  |  |  |  |  |
New Jersey Infrastructure Bank [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Amount drawn |  |  |  |  | 6,100 |  |  |  |  |  |
Tidewater [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Loan amount |  |  | $ 1,200 |  |  |  |  |  |  |  |
Amount drawn |  |  | $ 1,100 |  |  |  |  |  |  |  |
Interest rate |  |  | 2.00% |  |  |  |  |  |  |  |
Maturity date |  |  | Feb. 01, 2036 |  |  |  |  |  |  |  |
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] |  |  |  |  |  |  |  |  |  |  |
Maximum borrowing amount |  |  |  |  |  |  |  | $ 10,000 |  |  | $ 900
Long-term debt |  |  |  |  | 8,400 |  |  |  |  |  |
Series 2018A [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of first mortgage bond | $ 7,100 |  |  |  |  |  |  |  |  |  |
Maturity date | Aug. 01, 2047 |  |  |  |  |  |  |  |  |  |
Series 2018A [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Interest rate | 3.00% |  |  |  |  |  |  |  |  |  |
Series 2018A [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Interest rate | 5.00% |  |  |  |  |  |  |  |  |  |
Series 2018B [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of first mortgage bond | $ 2,400 |  |  |  |  |  |  |  |  |  |
Maturity date | Aug. 01, 2047 |  |  |  |  |  |  |  |  |  |
Amortizing Secured Notes [Member] |  |  |  |  |  |  |  |  |  |  |
Schedule of Capitalization [Line Items] |  |  |  |  |  |  |  |  |  |  |
Long-term debt |  |  |  |  | $ 36,600 |  |  |  |  |  |

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