XML 44 R32.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Organization, Summary of Significant Accounting Policies and Recent Developments - Schedule of AFUDC Rates for Middlesex and Tidewater (Details) | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Middlesex [Member] |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Allowance for funds used during construction rates | 6.64% | 6.35% | 6.35%
Tidewater [Member] |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Allowance for funds used during construction rates | 7.92% | 7.92% | 7.92%

X
- Definition Effective rate, including composite rate, of cost of financing additions to qualifying regulated assets, commonly called allowance for funds used during construction. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478698/980-835-25-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 835 -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479123/980-835-45-1 + Details
Name: | us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesGeneralDisclosuresLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=msex_MiddlesexMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=msex_TidewaterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |