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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 |  |  |  |  |

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