Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 24, 2023	Jun. 30, 2022
Document Information Line Items
Entity Registrant Name	MIDDLESEX WATER COMPANY
Trading Symbol	MSEX
Document Type	10-K/A
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		17,642,147
Entity Public Float			$ 1,505,071,215
Amendment Flag	true
Amendment Description	Middlesex Water Company (the Company) is filing this Amendment No. 1 to the Annual Report on Form 10-K (this Form 10-K/A) for the fiscal year ended December 31, 2022, originally filed with the Securities and Exchange Commission (the SEC) on February 24, 2023 (the 2022 Form 10-K) to make certain changes described below.In the 2022 Form 10-K, the Company indicated and reported that, based on its assessment at such time, its internal control over financial reporting was operating as designed and were effective. The 2022 Form 10-K included Baker Tilly US, LLP’s (Baker Tilly) Report of Independent Registered Public Accounting Firm dated February 24, 2023, that concluded “in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2022, based on criteria established in Internal Control – Integrated Framework: (2013) issued by COSO.”Subsequent to the issuance of the Company’s 2022 Form 10-K, the Company’s independent registered public accounting firm, Baker Tilly, conducted a routine internal quality review of its integrated audit of the Company’s 2022 consolidated financial statements and internal control over financial reporting as of December 31, 2022. As a result of this review, Baker Tilly re-examined the Company’s information technology general controls (ITGCs) in the areas of user access and change management over certain information technology (IT) systems that support the Company’s financial reporting processes. Certain of those controls were found to be deficient because of a lack of sufficient IT control processes designed to prevent or detect unauthorized changes in applications and data in selected IT environments. It has therefore been concluded that automated and manual process controls dependent on ITGCs were not effective. On November 1, 2023, the Company determined, and Baker Tilly concurred, that the ITGCs deficiency and the resulting impact on other controls constitutes a material weakness in the Company’s internal control over financial reporting as of December 31, 2022. For a more detailed description of this material weakness, refer to Part II, Item 9A, “Controls and Procedures.”Notwithstanding the newly identified material weakness referred to above, Management, including our Principal Executive Officer and Principal Financial Officer, believes that the financial statements contained in the 2022 Form 10-K fairly present, in all material respects, the financial condition, results of operations and cash flows of the Company for all periods presented in accordance with accounting principles generally accepted in the United States of America.In accordance with Rule 12b-15 of the Securities Exchange Act of 1934, as amended (the Exchange Act), this Form 10-K/A is being filed to (i) amend the Company’s Forward-Looking Statement, (ii) amend the Company’s risk factors included in Part I. Item 1A, (iii) replace Baker Tilly’s audit report with the revised audit report included in Part II, Item 8 to reflect the newly identified material weakness as of December 31, 2022, (iv) amend the Company’s disclosure on controls and procedures included in Part II, Item 9A, and (v) amend Part IV - Item 15 Exhibits and Financial Statement Schedules to replace Baker Tilly’s consent of independent registered public accounting firm with an updated consent of independent registered public accounting firm and include currently dated certifications from the Company’s Chief Executive Officer and Chief Financial Officer as required by Section 302 and 906 of the Sarbanes-Oxley Act of 2002.Please note that the only changes to the 2022 Form 10-K are those related to the matters described herein and only in the Items listed above. Except as described above, no changes have been made to the 2022 Form 10-K, and this Form 10-K/A does not modify, amend or update any of the other financial information or other information contained in the 2022 Form 10-K. In addition, in accordance with SEC rules, this Form 10-K/A includes an updated auditor consent as Exhibit 23.1 and updated certifications from our Chief Executive Officer and Chief Financial Officer as Exhibits 31, 31.1, 32 and 32.1. Except for the foregoing changes, the information in this Form 10-K/A is as of February 24, 2023, the filing date of the original Form 10-K for the year ended December 31, 2022, and has not been updated for the events subsequent to that date other than as discussed above.
Entity Central Index Key	0000066004
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Document Annual Report	true
Document Transition Report	false
Entity File Number	0-422
Entity Incorporation, State or Country Code	NJ
Entity Tax Identification Number	22-1114430
Entity Address, Address Line One	485C Route 1 South
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Iselin
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08830
City Area Code	(732)
Local Phone Number	634-1500
Title of 12(b) Security	Common Stock, No Par Value
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Auditor Name	Baker Tilly US, LLP
Auditor Location	Philadelphia
Auditor Firm ID	23
Document Financial Statement Error Correction [Flag]	false