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Commitments and Contingent Liabilities (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 9 Months Ended |
--- | --- | ---
Sep. 30, 2014 | Dec. 31, 2013
Period of wastewater agreement | 20 years |
Water and wastewater system agreement | USA-PA operates the City of Perth Amboy, New Jersey'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 for the operation and maintenance of the Perth Amboy wastewater collection system. |
Budgeted construction cost for construction program, 2014 | $ 26.6 |
Guarant liabilty for AWM's performance | $ 0.3 | $ 0.4
NJ Water Supply Authority [Member] |  |
Commitment to purchase water | Middlesex has an agreement with the New Jersey Water Supply Authority (NJWSA) for the purchase of untreated water through November 30, 2023 |
Purchase commitment expiration date of contract | Nov. 30, 2023 |
Water purchase per commitment | 27 |
Regulated Water Authority [Member] |  |
Commitment to purchase water | Middlesex also has an agreement with a non-affiliated regulated water utility for the purchase of treated water. |
Purchase commitment expiration date of contract | Feb. 27, 2016 |
Water purchase per commitment | 3 |

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- Definition This item represents a non-contingent liability for the fair value of an obligation to stand ready to perform over the term of a guaranty issued in the event that specified triggering events or conditions occur. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.15) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.15) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 25 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=7661617&loc=d3e11049-110243 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 25 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=7661617&loc=d3e11019-110243 + Details
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