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Cover - USD ($)
 12 Months Ended
Dec. 31, 2024
Feb. 26, 2025
Jun. 30, 2024
Document Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Transition Report false    
Document Financial Statement Error Correction [Flag] false    
Entity Interactive Data Current Yes    
ICFR Auditor Attestation Flag true    
Amendment Flag false    
Document Period End Date Dec. 31, 2024    
Document Fiscal Year Focus 2024    
Document Fiscal Period Focus FY    
Documents Incorporated by Reference [Text Block]

Proxy Statement to be filed in connection with the Registrant’s Annual Meeting of Stockholders to be held on May 20, 2025, which will be filed with the Securities and Exchange Commission within 120 days of the end of our 2024 fiscal year, is incorporated by reference into Part III of this Annual Report on Form 10-K to the extent described herein.

    
Entity Information [Line Items]      
Entity Registrant Name MIDDLESEX WATER COMPANY    
Entity Central Index Key 0000066004    
Entity File Number 0-422    
Entity Tax Identification Number 22-1114430    
Entity Incorporation, State or Country Code NJ    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Shell Company false    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Public Float     $ 906,502,416
Entity Contact Personnel [Line Items]      
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    
Entity Phone Fax Numbers [Line Items]      
City Area Code (732)    
Local Phone Number 634-1500    
Entity Listings [Line Items]      
Title of 12(b) Security Common Stock, No Par Value    
Trading Symbol MSEX    
Security Exchange Name NASDAQ    
Entity Common Stock, Shares Outstanding   17,887,454