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Significant Accounting Policies, Regulatory Assets and Liabilities (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2024
USD ($)
ServiceLine
Dec. 31, 2023
USD ($)
Dec. 31, 2014
USD ($)
Assets [Abstract]      
Regulatory assets $ 54,061 $ 48,949  
Liabilities [Abstract]      
Regulatory liabilities 44,811 43,633  
Excess Accumulated Deferred Income Taxes on Accelerated Depreciation [Member]      
Liabilities [Abstract]      
Regulatory liabilities 13,090 13,286  
Postretirement Benefits [Member]      
Liabilities [Abstract]      
Regulatory liabilities 22,825 21,196  
Income Taxes [Member]      
Liabilities [Abstract]      
Regulatory liabilities $ 6,520 6,516  
Income Taxes [Member] | Minimum [Member]      
Liabilities [Abstract]      
Remaining recovery period 1 year    
Income Taxes [Member] | Maximum [Member]      
Liabilities [Abstract]      
Remaining recovery period 50 years    
IRS TPR Catch-Up Deduction [Member]      
Liabilities [Abstract]      
Regulatory liabilities $ 2,376 2,635 $ 3,887
Remaining recovery period 9 years    
Approved amortization period 15 years    
Income Taxes [Member]      
Assets [Abstract]      
Regulatory assets $ 40,880 35,885  
Unrealized Swap Losses [Member]      
Assets [Abstract]      
Regulatory assets $ 382 632  
Unrealized Swap Losses [Member] | Minimum [Member]      
Assets [Abstract]      
Remaining recovery period 1 year    
Unrealized Swap Losses [Member] | Maximum [Member]      
Assets [Abstract]      
Remaining recovery period 5 years    
Utility Plant Retirement Costs [Member]      
Assets [Abstract]      
Regulatory assets $ 10,221 9,592  
Remaining recovery period 5 years    
Customer-Owned Lead Service Line Replacements [Member]      
Assets [Abstract]      
Regulatory assets $ 1,173 1,257  
Remaining recovery period 4 years    
Number of lead customer-owned service lines to be replaced annually | ServiceLine 400    
Term of tariff modification to replace customer-owned lead service lines 9 years    
Income Taxes on Customers' Advances for Construction and Contributions in Aid of Construction [Member]      
Assets [Abstract]      
Regulatory assets $ 1,176 1,250  
Service Life Study Expenses [Member]      
Assets [Abstract]      
Regulatory assets $ 14 19  
Remaining recovery period 3 years    
Rate Case Filing Expenses [Member]      
Assets [Abstract]      
Regulatory assets $ 215 $ 314  
Remaining recovery period 2 years