Capitalization (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Jul. 31, 2016
Schedule of Capitalization [Line Items]
Issuance of shares under the DRP, shares	7,845	15,488
Issuance of shares under the DRP	$ 300	$ 400
Other long term debt	61,600		$ 59,700
Customer advances	20,868		$ 20,846
New Jersey SRF Program [Member]
Schedule of Capitalization [Line Items]
Maximum borrowing amount	37,000			$ 4,000
New Jersey SRF Program [Member] | 2017 Renew Program [Member]
Schedule of Capitalization [Line Items]
Maximum borrowing amount	$ 10,000