v3.26.1
Capitalization - Narrative (Details)
$ / shares in Units, $ in Thousands
 1 Months Ended 3 Months Ended 6 Months Ended
Feb. 28, 2026
USD ($)
May 31, 2025
USD ($)
May 31, 2024
USD ($)
loan
Jun. 30, 2026
USD ($)
$ / shares
shares
Mar. 31, 2026
USD ($)
shares
Jun. 30, 2025
USD ($)
shares
Jun. 30, 2026
USD ($)
$ / shares
shares
Jun. 30, 2025
USD ($)
shares
Dec. 31, 2025
USD ($)
Sep. 30, 2024
USD ($)
Class of Stock [Line Items]                    
At-the-market program common stock issuance       $ 11,327 $ 2,662 $ 3,604        
Total net proceeds from shares issued and sold under agreement             $ 14,425 $ 4,054    
Debt drawn down             26,496 $ 886    
Secured Debt | Pinelands Water Company                    
Class of Stock [Line Items]                    
Interest rate 6.17%                  
Debt repaid $ 3,700                  
Secured Debt | Pinelands Wastewater Company                    
Class of Stock [Line Items]                    
Interest rate 6.17%                  
Debt repaid $ 3,400                  
June 2026 Delaware State Revolving Fund | Loans Payable | Middlesex                    
Class of Stock [Line Items]                    
Borrowing amount       17,800     17,800      
June 2026 ACB (CoBank) Revolving Fund | Loans Payable | Tidewater                    
Class of Stock [Line Items]                    
Borrowing amount       $ 25,000     $ 25,000      
Interest rate       6.72%     6.72%      
September 2024 Delaware SRF | Loans Payable | Tidewater                    
Class of Stock [Line Items]                    
Borrowing amount                   $ 2,200
Interest rate                   0.00%
Debt drawn down             $ 1,800      
May 2024 Delaware SRF | Loans Payable | Tidewater                    
Class of Stock [Line Items]                    
Borrowing amount     $ 5,600              
Interest rate     2.00%              
Debt drawn down             2,100      
Number of debt instruments | loan     4              
December 2025 Delaware State Revolving Fund | Loans Payable | Tidewater                    
Class of Stock [Line Items]                    
Borrowing amount                 $ 1,000  
Interest rate                 2.00%  
December 2025 Delaware State Revolving Fund | Loans Payable | Southern Shores                    
Class of Stock [Line Items]                    
Borrowing amount                 $ 400  
Interest rate                 0.00%  
Debt drawn down             200      
Amortizing Secured Notes And State Revolving Trust Notes | Loans Payable                    
Class of Stock [Line Items]                    
Carrying amount of debt       $ 276,800     276,800   $ 259,500  
Construction Advances | Loans Payable                    
Class of Stock [Line Items]                    
Carrying amount of debt       $ 26,900     $ 26,900   $ 25,500  
ATM Equity Sales Agreement                    
Class of Stock [Line Items]                    
Aggregate gross sales price   $ 110,000                
Number of shares issued and sold under agreement (in shares) | shares       215,722     265,027      
Weighted average price per share of shares issued and sold under agreement (in dollars per share) | $ / shares       $ 53.31     $ 53.59      
Total net proceeds from shares issued and sold under agreement       $ 11,300     $ 14,000      
Aggregate gross sales price of shares remaining to be issued under agreement       $ 65,800     $ 65,800      
Common Stock                    
Class of Stock [Line Items]                    
Number of common shares issued (in shares) | shares       216,000 49,000 64,000        
At-the-market program common stock issuance       $ 11,327 $ 2,662 $ 3,604        
Middlesex Water Company Investment Plan | Common Stock                    
Class of Stock [Line Items]                    
Number of common shares issued (in shares) | shares             8,203 8,130    
At-the-market program common stock issuance             $ 400 $ 400