Income Taxes (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Position	Dec. 31, 2018 USD ($)	Dec. 31, 2017
Provisions for Income Taxes [Abstract]
Federal current	$ 1,148	$ 1,715
State current	451	718
Federal deferred	475	216
State deferred	205	(119)
Federal investment tax credit, net of current utilization	(39)	(39)
Total income taxes	2,240	2,491
Reconciliation of Statutory Federal Tax Provision to Total Provision [Abstract]
Statutory Federal tax provision	3,495	3,332
State income taxes, net of Federal benefit	574	471
IRS TPR deduction	(1,642)	(1,307)
Tax-exempt interest	(25)	(22)
Amortization of investment tax credit	(39)	(39)
Cash value of life insurance	6	(13)
Amortization of excess accumulated deferred income taxes on accelerated depreciation	(149)	0
Other, net	20	69
Total income taxes	2,240	2,491
Regulatory Liabilities [Abstract]
Regulatory liabilities	$ 25,399	$ 26,814
Federal corporate tax rate	21.00%	21.00%	34.00%
Deferred Tax Assets [Abstract]
Reserve for doubtful accounts	$ 88	$ 88
Compensated absences	148	147
Deferred compensation	1,276	1,143
Excess accumulated deferred income taxes on accelerated depreciation	4,047	4,098
Deferred taxes associated with the gross-up of revenues necessary to return, in rates, the effect of temporary differences	2,104	2,077
Customers' advances for construction and contributions in aid of construction	998	577
Revenue reduction for tax rate change	7	333
Pensions	0	256
Other costs deducted for book, not for tax	69	40
Total deferred tax assets	8,737	8,759
Deferred Tax Liabilities [Abstract]
Accelerated depreciation	28,891	28,479
Basis differences from IRS TPR	11,311	9,367
Investment tax credit	384	411
Deferred taxes associated with the gross-up of revenues necessary to recover, in rates, the effect of temporary differences	6,987	6,124
Pension	525	0
Tax effect of pension regulatory asset	106	887
Unamortized debt issuance costs	531	197
Other costs deducted for tax, not for book	428	256
Total deferred tax liabilities	49,163	45,721
Net deferred tax liability	40,426	36,962
Valuation allowance	0	0
Uncertain tax positions	$ 0
Open tax year	2016 2017 2018
Number of new tax positions taken | Position	0
Interest or penalties	$ 0	1
IRS TPR Catch-Up Deduction [Member]
Regulatory Liabilities [Abstract]
Regulatory liabilities	$ 3,671	3,887
Approved amortization period	15 years
Amortization of catch-up deduction	$ (216)
IRS TPR Ongoing Deductions Member [Member]
Regulatory Liabilities [Abstract]
Ongoing TPR deduction	$ (1,426)	$ (1,307)