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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Part 2 (Details) - USD ($) $ in Thousands | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Jan. 31, 2017 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Aug. 03, 2020 | Jan. 31, 2019
Regulatory Assets [Abstract] |  |  |  |  |  |  |  |
Cash received for bond issuance |  | $ 30,000 |  |  |  |  |  |
Amortization period of other regulatory expense [Abstract] |  |  |  |  |  |  |  |
Deferred contract costs and other |  | 5 years |  |  |  |  |  |
Rate case studies |  | 5 years |  |  |  |  |  |
Goodwill |  | 50 years |  |  |  |  |  |
Deferred acquisition costs |  | 20 years |  |  |  |  |  |
Franchise costs |  | 80 years |  |  |  |  |  |
Regulatory assets net of amortization, comprise [Abstract] |  |  |  |  |  |  |  |
Regulatory assets, net |  | $ 6,321 | $ 6,473 |  |  |  |  |
Summary of other deferred assets net of amortization [Abstract] |  |  |  |  |  |  |  |
Investment in Co Bank |  | 4,850 | 4,374 |  |  |  |  |
Other deferred assets/goodwill |  | 247 | 935 |  |  |  | $ 623 |
Other |  | 5,097 | 5,309 |  |  |  |  |
Regulatory adjustment |  | 1,500 |  |  |  |  |  |
Impairment or Disposal of Long-Lived Assets [Abstract] |  |  |  |  |  |  |  |
Impairment |  | 0 | $ 0 | $ 0 |  |  |  |
Contributions in Aid of Construction [Abstract] |  |  |  |  |  |  |  |
Refund for contributions in aid of construction due to tax status change |  | $ 3,200 |  |  |  |  |  |
Regulatory Liabilities [Line Items] |  |  |  |  |  |  |  |
Federal corporate tax rate |  | 21.00% | 21.00% | 21.00% |  | 34.00% |  |
Decrease in the net deferred income tax liability |  |  | $ 24,300 |  | $ 24,300 |  |  |
Net regulatory liability amount |  |  | 22,800 |  | $ 22,800 |  |  |
Regulatory Liabilities |  | $ 21,260 | 21,681 |  |  |  |  |
Minimum [Member] |  |  |  |  |  |  |  |
Amortization period of other regulatory expense [Abstract] |  |  |  |  |  |  |  |
Amortization period of debt related cost | 15 years |  |  |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |  |
Amortization period of other regulatory expense [Abstract] |  |  |  |  |  |  |  |
Amortization period of debt related cost | 30 years |  |  |  |  |  |  |
Maryland [Member] |  |  |  |  |  |  |  |
Amortization period of other regulatory expense [Abstract] |  |  |  |  |  |  |  |
Rate proceedings |  | 5 years |  |  |  |  |  |
Delaware [Member] |  |  |  |  |  |  |  |
Amortization period of other regulatory expense [Abstract] |  |  |  |  |  |  |  |
Rate proceedings |  | 2 years 6 months |  |  |  |  |  |
DEPSC [Member] |  |  |  |  |  |  |  |
Regulatory Liabilities [Line Items] |  |  |  |  |  |  |  |
Net regulatory liability amount |  |  |  |  |  |  |  | $ 22,200
Regulatory liabilities, amortization period |  | 49 years 6 months |  |  |  |  |  |
MDPSC [Member] |  |  |  |  |  |  |  |
Regulatory Liabilities [Line Items] |  |  |  |  |  |  |  |
Net regulatory liability amount |  | $ 600 | 600 |  |  |  |  |
Utility Plant Retirement Cost Obligation [Member] |  |  |  |  |  |  |  |
Regulatory Liabilities [Line Items] |  |  |  |  |  |  |  |
Regulatory Liabilities |  | 149 | 126 |  |  |  |  |
Deferred Income Taxes [Member] |  |  |  |  |  |  |  |
Regulatory Liabilities [Line Items] |  |  |  |  |  |  |  |
Regulatory Liabilities |  | 21,111 | 21,555 |  |  |  |  |
Deferred Income Taxes [Member] |  |  |  |  |  |  |  |
Regulatory assets net of amortization, comprise [Abstract] |  |  |  |  |  |  |  |
Regulatory assets, net |  | 355 | 370 |  |  |  |  |
Deferred Contract Costs and Other [Member] |  |  |  |  |  |  |  |
Regulatory assets net of amortization, comprise [Abstract] |  |  |  |  |  |  |  |
Regulatory assets, net |  | 288 | 46 |  |  |  |  |
Debt Related Costs [Member] |  |  |  |  |  |  |  |
Regulatory assets net of amortization, comprise [Abstract] |  |  |  |  |  |  |  |
Regulatory assets, net |  | 4,902 | 5,233 |  |  |  |  |
Goodwill [Member] |  |  |  |  |  |  |  |
Regulatory assets net of amortization, comprise [Abstract] |  |  |  |  |  |  |  |
Regulatory assets, net |  | 273 | 281 |  |  |  |  |
Deferred Acquisition and Franchise Costs [Member] |  |  |  |  |  |  |  |
Regulatory assets net of amortization, comprise [Abstract] |  |  |  |  |  |  |  |
Regulatory assets, net |  | $ 503 | $ 543 |  |  |  |  |

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