0001174947-23-000678 | 10-Q | XBRL Viewer

Capitalization (Details) - Schedule of carrying amount and fair value of the bonds - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2023	Dec. 31, 2022
Schedule of Carrying Amount and Fair Value of Bonds [Abstract]
Carrying Amount	$ 146,496	$ 147,269

Capitalization (Details) - USD ($) $ in Millions	1 Months Ended			3 Months Ended
Capitalization (Details) - USD ($) $ in Millions	May 31, 2023	Apr. 30, 2023	Dec. 31, 2021	Mar. 31, 2023	Dec. 31, 2022	Nov. 30, 2021
Capitalization (Details) [Line Items]
Discount offering shares (in Shares)				200,000
Maturity date	2033	2044		2023
Borrowed loan				$ 20.0
Borrowing amount		$ 4.9		3.0		$ 5.0
Construction carrying amount				$ 22.3	$ 21.4	$ 1.0
Program loan amount			$ 5.0
Interest payment term				20 years

Commitments and Contingent Liabilities (Details) - Schedule of operating lease ROU assets - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Schedule Of Operating Lease Rou Assets Abstract
ROU Asset at Lease Inception	$ 7.3	$ 7.3
Accumulated Amortization	(3.6)	(3.5)
Current ROU Asset	$ 3.7	$ 3.8

Revenue Recognition from Contracts with Customers (Details) - Schedule of Operating Revenue - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Regulated Tariff Sales
Residential	$ 19,004	$ 19,152
Commercial	5,379	4,427
Industrial	2,839	2,595
Fire Protection	3,104	3,120
Wholesale	4,553	3,964
Non-Regulated Contract Operations	3,229	2,900
Other Non-Regulated Revenues	113	109
Inter-segment Elimination	$ (139)	$ (138)

Employee Benefit Plans (Details) - Schedule of components of net benefit cost - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Employee Benefit Plans (Details) - Schedule of components of net benefit cost [Line Items]
Interest Cost	$ 402	$ 331
Expected Return on Assets	(771)	(887)
Amortization of Unrecognized Losses	$ (48)

Label	Element	Value
Total Common Equity	msex_TotalCommonEquity	$ 403,355,000
Total Common Equity	msex_TotalCommonEquity	400,328,000
Total Common Equity	msex_TotalCommonEquity	$ 400,328,000
Renewal Date Of Line Of Credit	msex_RenewalDateOfLineOfCredit	Jan. 25, 2024
Renewal Date Of Line Of Credit	msex_RenewalDateOfLineOfCredit	Jan. 31, 2025
Renewal Date Of Line Of Credit	msex_RenewalDateOfLineOfCredit	Nov. 30, 2023
Change In Unbilled Revenues	msex_ChangeInUnbilledRevenues	$ 1,000
Change In Unbilled Revenues	msex_ChangeInUnbilledRevenues	875,000
Estimatedobligationexpenditure	msex_Estimatedobligationexpenditure	20,500,000
Preferred Stock Value1	msex_PreferredStockValue1
Preferred Stock Value1	msex_PreferredStockValue1
Outstanding Maturity Date	msex_OutstandingMaturityDate	April 2023
Outstanding Maturity Date	msex_OutstandingMaturityDate	June 2023
Construction Advances	msex_ConstructionAdvances	$ 22,297,000
Construction Advances	msex_ConstructionAdvances	21,382,000
Consolidated Net Income	msex_ConsolidatedNetIncome	5,324,000
Consolidated Net Income	msex_ConsolidatedNetIncome	11,513,000
Consolidated Net Income	msex_ConsolidatedNetIncome	544,000
Consolidated Net Income	msex_ConsolidatedNetIncome	587,000
Consolidated Net Income	msex_ConsolidatedNetIncome	5,868,000
Consolidated Net Income	msex_ConsolidatedNetIncome	12,100,000
Preferred Shares Authorized	msex_PreferredSharesAuthorized
Preferred Shares Authorized	msex_PreferredSharesAuthorized
Operations And Maintenance	msex_OperationsAndMaintenance	20,257,000
Operations And Maintenance	msex_OperationsAndMaintenance	19,139,000
Non Cash Consideration For Sale Of Subsidiary	msex_NonCashConsiderationForSaleOfSubsidiary	2,100,000
Non Cash Consideration For Sale Of Subsidiary	msex_NonCashConsiderationForSaleOfSubsidiary
Non Utility Assets Net	msex_NonUtilityAssetsNet	11,404,000
Non Utility Assets Net	msex_NonUtilityAssetsNet	$ 11,207,000
Longterm Purchase Commitment Expiration Date	msex_LongtermPurchaseCommitmentExpirationDate	Nov. 30, 2023
Longterm Purchase Commitment Expiration Date	msex_LongtermPurchaseCommitmentExpirationDate	Feb. 27, 2026
Deferred Charges And Other Assets	msex_DeferredChargesAndOtherAssets	$ 117,401,000
Deferred Charges And Other Assets	msex_DeferredChargesAndOtherAssets	116,593,000
Preliminary Survey And Investigation Charges	msex_PreliminarySurveyAndInvestigationCharges	2,809,000
Preliminary Survey And Investigation Charges	msex_PreliminarySurveyAndInvestigationCharges	2,806,000
Budgeted Construction Cost	msex_BudgetedConstructionCost	111,000,000
Employee Benefit Plans	msex_EmployeeBenefitPlans	9,284,000
Employee Benefit Plans	msex_EmployeeBenefitPlans	$ 8,689,000

Commitments and Contingent Liabilities (Details) - Schedule of purchased water costs - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Schedule Of Purchased Water Costs Abstract
Treated	$ 1,383	$ 747
Untreated	$ 802	$ 811