Rate and Regulatory Matters (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended									12 Months Ended
	Nov. 30, 2016	Jun. 30, 2016	Apr. 30, 2016	Nov. 30, 2015	Oct. 31, 2015	Aug. 31, 2015	Oct. 31, 2014	Aug. 31, 2014	Jun. 30, 2014	Dec. 31, 2016	Dec. 31, 2015
Regulatory Liabilities [Line Items]
Regulatory Liability - Cost of Utility Plant Removal										$ 11,337	$ 10,876
Acquisition premiums to be recovered										500
Pinelands Water Company [Member]
Regulatory Liabilities [Line Items]
Approved increase in annual operating revenues			$ 200
Originally filed increase in annual operating revenue					$ 500
Pinelands Wastewater [Member]
Regulatory Liabilities [Line Items]
Approved increase in annual operating revenues			$ 100
Twin Lakes [Member]
Regulatory Liabilities [Line Items]
Approved increase in annual operating revenues		$ 100
Originally filed increase in annual operating revenue				$ 200
New Jersey Board Of Public Utilities [Member]
Regulatory Liabilities [Line Items]
Approved increase in annual operating revenues						$ 5,000
New Jersey Board Of Public Utilities [Member] | Middlesex [Member]
Regulatory Liabilities [Line Items]
Approved increase in annual operating revenues									$ 4,200
Originally filed increase in annual operating revenue	$ 100
Amended filed increase in annual operating revenue										5,000
Base rate amount									$ 208,600	$ 219,000
Return on equity									9.75%	9.75%
New Jersey Board Of Public Utilities [Member] | TESI [Member]
Regulatory Liabilities [Line Items]
Approved increase in annual operating revenues							$ 100
Delaware Public Service Commission [Member] | Tidewater [Member]
Regulatory Liabilities [Line Items]
Approved increase in annual operating revenues										$ 300
Amended filed increase in annual operating revenue								$ 800
Base rate amount										$ 208,600
Return on equity										9.75%
Delaware Public Service Commission [Member] | TESI [Member]
Regulatory Liabilities [Line Items]
Approved increase in annual operating revenue (percentage)							33.50%
Delaware Public Service Commission [Member] | Southern Shores [Member]
Regulatory Liabilities [Line Items]
Originally filed increase in annual operating revenue										$ 100