Commitments and Contingent Liabilities (Details Narrative) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Commitments And Contingent Liabilities Details Narrative
Term of water and wastewater system agreement	USA-PA operates the City of Perth Amboy, NJ's water and wastewater systems under a 20-year agreement, which expires in 2018. In connection with the agreement with Perth Amboy, USA-PA entered into a 20-year subcontract with a wastewater operating company
Commitment of purchase of untreated water	Middlesex has an agreement with the NJWSA for the purchase of untreated water through November 30, 2023, which provides for an average purchase of 27 million gallons a day (mgd). Pricing is set annually by the NJWSA through a public rate making process.
Minimum treated water purchase commitment	Middlesex also has an agreement with a non-affiliated regulated water utility for the purchase of treated water. This agreement, which expires February 27, 2016, provides for the minimum purchase of 3 mgd of treated water with provisions for additional purchases.
Budgeted construction cost for construction program, next year	$ 21,700