v3.25.2
Summary of Significant Accounting Policies (Details)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
USD ($)
state
contract
shares
Mar. 31, 2025
USD ($)
Jun. 30, 2024
USD ($)
shares
Mar. 31, 2024
USD ($)
Jun. 30, 2025
USD ($)
state
contract
customer
registrant
shares
Jun. 30, 2024
USD ($)
shares
Aug. 05, 2025
USD ($)
May 29, 2025
USD ($)
Mar. 13, 2025
USD ($)
Feb. 12, 2025
USD ($)
Dec. 31, 2024
USD ($)
Feb. 27, 2024
USD ($)
Summary of significant accounting policies                        
Number of customers | customer         1,000,000              
Number of states in which entity operates | state 10       10              
Property installed by developers and conveyed         $ 14,659 $ 3,625            
Number of registrants filing combined report | registrant         2              
Issuance of Common Shares from an at-the-market offering program, net of issuance costs   $ 25,648 $ 16,724 $ 15,584                
Sale of stock, maximum consideration on transaction                       $ 200,000
Agreement term (in years)         3 years              
Sale of stock, number of shares issued in transaction (in shares) | shares 0   227,667   334,548 455,648            
Sale of stock, consideration received on transaction     $ 16,800   $ 25,800 $ 33,000            
Payments for commissions $ 200   300   400 500            
Payments of stock issuance costs 100                      
Sale of Stock, remaining available for sale 82,900       $ 82,900              
Debt instrument term (in years)         5 years              
Incremental expansion of borrowing capacity 30,000       $ 30,000              
Notes payable to banks 153,000       153,000           $ 165,000  
Syndicated Revolving Credit Facility                        
Summary of significant accounting policies                        
Notes payable to banks 143,000       143,000              
GSWC                        
Summary of significant accounting policies                        
Property installed by developers and conveyed         $ 14,659 3,625            
Issuance of Common Shares from an at-the-market program, net of issuance costs (in shares) | shares         3.6500              
Issuance of Common Shares from an at-the-market offering program, net of issuance costs 50,005       $ 50,000              
Incremental expansion of borrowing capacity 75,000       75,000              
Notes payable to banks $ 9,000       $ 9,000           $ 0  
Intercompany borrowings payment term         24 months              
Ratio of Indebtedness to EBITDA 8       8              
GSWC | Financing Application                        
Summary of significant accounting policies                        
Regulatory rate case filings requested authorization for debt and equity issuance                 $ 750,000      
GSWC | Syndicated Revolving Credit Facility                        
Summary of significant accounting policies                        
Notes payable to banks $ 9,000       $ 9,000              
GSWC | Unsecured private-placement notes                        
Summary of significant accounting policies                        
Face amount of debt 100,000       $ 100,000     $ 100,000        
GSWC | Series A Senior Notes at a coupon rate of 5.65% due May 29, 2037                        
Summary of significant accounting policies                        
Face amount of debt               $ 75,000        
Stated interest rate percentage               5.30%        
GSWC | Series B Senior Notes at a coupon rate of 5.65% due May 29, 2037                        
Summary of significant accounting policies                        
Face amount of debt               $ 25,000        
Stated interest rate percentage               5.65%        
GSWC | Water:                        
Summary of significant accounting policies                        
Number of customers | customer         265,000              
GSWC | Water: | San Juan Oak                        
Summary of significant accounting policies                        
Service connections | customer         1,300              
Property installed by developers and conveyed         $ 10,700              
BVES                        
Summary of significant accounting policies                        
Payments to affiliate for corporate office administrative and general costs 800   700   $ 1,900 1,700            
Intercompany borrowings payment term         24 months              
Maximum borrowing capacity on line of credit 65,000       $ 65,000              
Face amount of debt                   $ 50,000    
BVES | Syndicated Revolving Credit Facility                        
Summary of significant accounting policies                        
Notes payable to banks 1,000       1,000              
BVES | Unsecured private-placement notes                        
Summary of significant accounting policies                        
Face amount of debt 50,000       $ 50,000              
BVES | Electric:                        
Summary of significant accounting policies                        
Number of customers | customer         25,000              
ASUS                        
Summary of significant accounting policies                        
Payments to affiliate for corporate office administrative and general costs $ 1,200   $ 1,200   $ 2,800 $ 2,800            
Bay State Utility Service LLC (" BSUS")                        
Summary of significant accounting policies                        
Number of contracts with 15 year contract | contract 1       1              
Bay State Utility Service LLC (" BSUS") | Contracted services:                        
Summary of significant accounting policies                        
Period of fixed price contracts to operate and maintain water systems at various military bases         15 years              
Maximum | Syndicated Revolving Credit Facility                        
Summary of significant accounting policies                        
Current borrowing capacity $ 195,000       $ 195,000              
Maximum | Syndicated Revolving Credit Facility | Subsequent Event                        
Summary of significant accounting policies                        
Current borrowing capacity             $ 195,000          
Maximum | GSWC                        
Summary of significant accounting policies                        
Ratio of Indebtedness to Net Capital 0.6667       0.6667              
Maximum | GSWC | Syndicated Revolving Credit Facility                        
Summary of significant accounting policies                        
Current borrowing capacity $ 200,000       $ 200,000              
Maximum | ASUS                        
Summary of significant accounting policies                        
Period of fixed price contracts to operate and maintain water systems at various military bases         50 years              
Minimum | Syndicated Revolving Credit Facility                        
Summary of significant accounting policies                        
Current borrowing capacity $ 165,000       $ 165,000              
Minimum | ASUS                        
Summary of significant accounting policies                        
Period of fixed price contracts to operate and maintain water systems at various military bases         14 years