INCOME TAXES (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 31, 2019
Income Taxes [Abstract]
Federal corporate tax rate	21.00%	21.00%	21.00%		34.00%
Decrease in the net deferred income tax liability		$ 24,300,000		$ 24,300,000
Net regulatory liability amount		22,800,000		22,800,000
Income Tax Examination, Operating Loss Carryforwards [Abstract]
Valuation allowance	$ 546,000	493,000
State income taxes [Abstract]
Current	1,216,000	2,348,000	$ 2,405,000
Deferred	776,000	(279,000)	(610,000)
Total state income tax expense	1,992,000	2,069,000	1,795,000
Federal income taxes [Abstract]
Current	2,144,000	5,725,000	6,015,000
Deferred	1,601,000	(2,110,000)	(2,629,000)
Total federal income tax expense	3,745,000	3,615,000	3,386,000
Reconciliation of effective tax rate [Abstract]
Income before federal and state income taxes	$ 22,564,000	$ 22,501,000	$ 20,106,000
Income before federal and state income taxes	100.00%	100.00%	100.00%
Income Tax Expense (Benefit) [Abstract]
Amount computed at statutory rate	$ 4,738,000	$ 4,725,000	$ 4,222,000
Amount computed at statutory rate	21.00%	21.00%	21.00%		34.00%
State income tax-net of federal tax benefit	$ 1,600,000	$ 1,704,000	$ 1,414,000
State income tax-net of federal tax benefit	7.10%	7.60%	7.00%
Regulatory liability adjustment	$ (451,000)	$ (451,000)	$ (451,000)
Regulatory liability adjustment	(2.00%)	(2.00%)	(2.20%)
Other	$ (150,000)	$ (294,000)	$ (4,000)
Other	(0.70%)	(1.30%)	0.00%
Total income tax expense	$ 5,737,000	$ 5,684,000	$ 5,181,000
Total effective income tax rate	25.40%	25.30%	25.80%
Deferred tax assets related to [Abstract]
Federal and state operating loss carry-forwards	$ 793,000	$ 629,000
Valuation allowance	(546,000)	(493,000)
Bad debt allowance	120,000	240,000
Stock options	122,000	148,000
Other	(10,000)	75,000
Total deferred tax assets	479,000	599,000
Deferred tax liabilities related to [Abstract]
Property plant and equipment basis differences	(51,102,000)	(48,536,000)
Bond retirement costs	(1,134,000)	(1,210,000)
Property taxes	(593,000)	(481,000)
Other	(783,000)	(685,000)
Total deferred tax liabilities	(53,612,000)	(50,912,000)
Net deferred tax liability	(53,133,000)	(50,313,000)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense [Abstract]
Balance at beginning of year	209,000	271,000
Additions based on tax positions related to the current year	0	0
Additions based on tax positions related to prior years	19,000	21,000
Reductions for tax positions of prior years	0	(83,000)
Lapses in statutes of limitations	(26,000)	0	$ (26,000)
Balance at end of year	$ 202,000	209,000	271,000
Minimum [Member]
Income Tax Examination, Operating Loss Carryforwards [Abstract]
Operating loss carryforwards expiration period	2022
Maximum [Member]
Income Tax Examination, Operating Loss Carryforwards [Abstract]
Operating loss carryforwards expiration period	2042
Valuation Allowance for Deferred Tax Assets [Member]
Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning Of Period	$ 493,000	335,000	396,000
Additions Charged to Costs and Expenses	53,000	158,000	41,000
Deductions	0	0	(102,000)
Balance at End of Period	546,000	493,000	$ 335,000	$ 396,000
DEPSC [Member]
Income Taxes [Abstract]
Net regulatory liability amount						$ 22,200,000
Amortization of regulatory liability		$ 22,200,000
Amortization period of regulatory liability		49 years 6 months
MDPSC [Member]
Income Taxes [Abstract]
Net regulatory liability amount	600,000	$ 600,000
State Authorities [Member]
Income Tax Examination, Operating Loss Carryforwards [Abstract]
Net operating loss carry-forwards	$ 11,900,000