XML 54 R36.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: