Cover - shares	9 Months Ended
	Sep. 30, 2023	Nov. 09, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
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 Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Contact Personnel [Line Items]
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
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
Trading Symbol	MSEX
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		17,806,696