XML 21 R55.htm IDEA: XBRL DOCUMENT v2.4.1.9

Employee Benefit Plans (Schedule of Fair Value of Other Benefits Plan Assets) (Details) (Other Benefits Plan [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 27,535us-gaap_DefinedBenefitPlanFairValueOfPlanAssets	$ 25,145us-gaap_DefinedBenefitPlanFairValueOfPlanAssets	$ 20,408us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Mutual Funds - Small Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	491us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsSmallCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	290us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsSmallCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Small Cap Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	82us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsSmallCapGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Mid Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	292us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	264us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Mid Cap Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	121us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	470us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Mid Cap Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	768us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	658us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Large Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10,516us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsLargeCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	8,650us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsLargeCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Foreign Small Mid Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	119us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignSmallMidGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	361us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignSmallMidGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Foreign Large Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	735us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	780us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Foreign Large Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		151us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Foreign Large Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	113us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	86us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Pacific Asia/ex-Japan Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		125us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsPacificAsiaexJapanStockMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Diversified Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	371us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsDiversifiedEmergingMarketsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	195us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsDiversifiedEmergingMarketsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Preferred Stock Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		110us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsPreferredStockIndexMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Mutual Funds - Real Estate Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	62us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsRealEstateIndexMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	59us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsRealEstateIndexMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Money Market Funds - Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	782us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MoneyMarketFundsCashCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	895us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MoneyMarketFundsCashCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Preferred Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	221us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_PreferredEquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Agency/US/State/Municipal Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12,862us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_AgencyUsStateMunicipalDebtMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember	11,928us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_AgencyUsStateMunicipalDebtMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Commodities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		123us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_CommoditiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember
Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14,341us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	13,089us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Small Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	491us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsSmallCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	290us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsSmallCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Small Cap Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	82us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsSmallCapGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Mid Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	292us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	264us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Mid Cap Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	121us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	470us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Mid Cap Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	768us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	658us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsMidCapValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Large Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10,516us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsLargeCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	8,650us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsLargeCapCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Foreign Small Mid Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	119us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignSmallMidGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	361us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignSmallMidGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Foreign Large Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	735us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	780us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeCoreMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Foreign Large Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		151us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeGrowthMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Foreign Large Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	113us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	86us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsForeignLargeValueMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Pacific Asia/ex-Japan Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		125us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsPacificAsiaexJapanStockMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Diversified Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	371us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsDiversifiedEmergingMarketsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	195us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsDiversifiedEmergingMarketsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Preferred Stock Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		110us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsPreferredStockIndexMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Mutual Funds - Real Estate Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	62us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsRealEstateIndexMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member	59us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MutualFundsRealEstateIndexMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Money Market Funds - Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	450us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_MoneyMarketFundsCashCashEquivalentsMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Preferred Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	221us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_PreferredEquitySecuritiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Agency/US/State/Municipal Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		767us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_AgencyUsStateMunicipalDebtMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 1 [Member] | Commodities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		123us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis = msex_CommoditiesMember / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member
Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,194us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member	12,056us-gaap_DefinedBenefitPlanFairValueOfPlanAssets / us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis = us-gaap_OtherPensionPlansDefinedBenefitMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member
Fair Value, Level 2 [Member] | Mutual Funds - Small Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Fair Value, Level 2 [Member] | Mutual Funds - Small Cap Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Fair Value, Level 2 [Member] | Mutual Funds - Mid Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Fair Value, Level 2 [Member] | Mutual Funds - Mid Cap Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Fair Value, Level 2 [Member] | Mutual Funds - Mid Cap Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Fair Value, Level 2 [Member] | Mutual Funds - Large Cap Core [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Fair Value, Level 2 [Member] | Mutual Funds - Foreign Large Growth [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Fair Value, Level 2 [Member] | Mutual Funds - Foreign Large Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
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Defined Benefit Plan Disclosure [Line Items]
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Defined Benefit Plan Disclosure [Line Items]
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Defined Benefit Plan Disclosure [Line Items]
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
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Defined Benefit Plan Disclosure [Line Items]
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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 35

-Paragraph 50

-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

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