Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2023	Apr. 28, 2023
Document Information Line Items
Entity Registrant Name	MIDDLESEX WATER COMPANY
Trading Symbol	MSEX
Document Type	10-Q/A
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		17,681,092
Amendment Flag	true
Amendment Description	Middlesex Water Company (the Company) is filing this Amendment No. 1 to the Quarterly Report on Form 10-Q (this Form 10-Q/A) for the quarterly period ended March 31, 2023, originally filed with the Securities and Exchange Commission (the SEC) on May 1, 2023 (the “March 31, 2023 Form 10-Q”) to make certain changes described below.In the March 31, 2023 Form 10-Q, the Company indicated and reported that, based on its assessment at such time, its disclosure controls and procedures were effective.Subsequent to the issuance of the Company’s March 31, 2023 Form 10-Q, the Company’s independent registered public accounting firm, Baker Tilly US, LLP (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 and through the period covered by this report and that the Company’s disclosure controls and procedures were not effective as of March 31, 2023. For a more detailed description of this material weakness, refer to Part I, Item 4, “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 March 31, 2023 Form 10-Q 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-Q/A is being filed to (i) amend the Company’s disclosure on controls and procedures included in Part I, Item 4, (ii) amend Part II, Item 1A Risk Factors and (ii) amend Part II, Item 6 Exhibits to 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 March 31, 2023 Form 10-Q 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 March 31, 2023 Form 10-Q, and this Form 10-Q/A does not modify, amend or update any of the other financial information or other information contained in the March 31, 2023 Form 10-Q. In addition, in accordance with SEC rules, this Form 10-Q/A includes updated certifications from our Chief Executive Officer and Chief Financial Officer as Exhibits 31.1, 31.2, 32.1 and 32.2. Except for the foregoing changes, the information in this Form 10-Q/A is as of May 1, 2023, the filing date of the original Form 10-Q for the quarterly period ended March 31, 2023, 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 Filer Category	Large Accelerated Filer
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Quarterly 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 One South
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
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes