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v3.23.1

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
Fair Value | $ 137,983 | $ 138,756

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- References No definition available. + Details
Name: | msex_CapitalizationDetailsScheduleofcarryingamountandfairvalueofthebondsLineItems
Namespace Prefix: | msex_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Carrying Amount. + References No definition available. + Details
Name: | msex_CarryingAmount
Namespace Prefix: | msex_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
Name: | us-gaap_LongTermDebtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant