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%