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Significant Accounting Policies, Regulatory Assets and Liabilities (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2023
USD ($)
ServiceLine
Dec. 31, 2022
USD ($)
Dec. 31, 2014
USD ($)
Assets [Abstract]      
Regulatory assets $ 48,949 $ 42,545  
Liabilities [Abstract]      
Regulatory liabilities 43,633 38,041  
Excess Accumulated Deferred Income Taxes on Accelerated Depreciation [Member]      
Liabilities [Abstract]      
Regulatory liabilities 13,286 13,483  
Postretirement Benefits [Member]      
Liabilities [Abstract]      
Regulatory liabilities 21,196 14,906  
Income Taxes [Member]      
Liabilities [Abstract]      
Regulatory liabilities $ 6,516 6,758  
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 $ 2,635 2,894 $ 3,887
Remaining recovery period 10 years    
Approved amortization period 15 years    
Income Taxes [Member]      
Assets [Abstract]      
Regulatory assets $ 35,885 29,779  
Unrealized Swap Losses [Member]      
Assets [Abstract]      
Regulatory assets $ 632 674  
Unrealized Swap Losses [Member] | Minimum [Member]      
Assets [Abstract]      
Remaining recovery period 1 year    
Unrealized Swap Losses [Member] | Maximum [Member]      
Assets [Abstract]      
Remaining recovery period 6 years    
Utility Plant Retirement Costs [Member]      
Assets [Abstract]      
Regulatory assets $ 9,592 9,060  
Remaining recovery period 5 years    
Customer-Owned Lead Service Line Replacements [Member]      
Assets [Abstract]      
Regulatory assets $ 1,257 1,260  
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 $ 1,250 1,353  
Service Life Study Expenses [Member]      
Assets [Abstract]      
Regulatory assets $ 19 24  
Remaining recovery period 4 years    
Rate Case Filing Expenses [Member]      
Assets [Abstract]      
Regulatory assets $ 314 $ 395  
Remaining recovery period 3 years