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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Part 4 (Details) - USD ($) |  |  |  | 12 Months Ended |
--- | --- | --- | --- | --- | ---
May 06, 2020 | May 08, 2019 | May 02, 2018 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 09, 2015
Stock Compensation Plans [Abstract] |  |  |  |  |  |  |
Granted (in shares) |  |  |  | 0 | 0 | 0 |
Compensation costs |  |  |  | $ 178,000 | $ 181,000 | $ 192,000 |
Unrecognized expense related to non-vested awards of restricted shares granted |  |  |  | 59,900 |  |  |
Accounts Receivable [Abstract] |  |  |  |  |  |  |
Increase in reserve for bad debt |  |  |  | 500,000 |  |  |
Expense related to allowance for doubtful accounts |  |  |  | 800,000 | 200,000 |  |
Summary of changes in entity's accounts receivable [Abstract] |  |  |  |  |  |  |
Gross accounts receivable |  |  |  | 11,024,000 | 7,177,000 |  |
Less allowance for doubtful accounts |  |  |  | 862,000 | 264,000 |  |
Total Accounts Receivable |  |  |  | 10,162,000 | 6,913,000 |  |
Summary of allowance for doubtful accounts [Abstract] |  |  |  |  |  |  |
Beginning balance |  |  |  | 264,000 | 232,000 |  |
Allowance adjustments |  |  |  | 754,000 | 198,000 |  |
Recoveries |  |  |  | 13,000 | 34,000 |  |
Write off of uncollectible accounts |  |  |  | (169,000) | (200,000) |  |
Ending balance |  |  |  | $ 862,000 | 264,000 | 232,000 |
Cash and Cash Equivalents [Abstract] |  |  |  |  |  |  |
Maximum maturity period of temporary cash investments considered as cash equivalents |  |  |  | 3 months |  |  |
Maryland [Member] |  |  |  |  |  |  |
Use of Estimates in the Preparation of Consolidated Financial Statements [Abstract] |  |  |  |  |  |  |
Payment arrangement minimum term |  |  |  | 12 months |  |  |
Delaware [Member] |  |  |  |  |  |  |
Use of Estimates in the Preparation of Consolidated Financial Statements [Abstract] |  |  |  |  |  |  |
Payment arrangement minimum term |  |  |  | 4 months |  |  |
Restricted Stock [Member] |  |  |  |  |  |  |
Stock Compensation Plans [Abstract] |  |  |  |  |  |  |
Compensation costs |  |  |  | $ 178,000 | 181,000 | $ 192,000 |
Customer accounts receivable - water [Member] |  |  |  |  |  |  |
Summary of changes in entity's accounts receivable [Abstract] |  |  |  |  |  |  |
Gross accounts receivable |  |  |  | 6,707,000 | 5,574,000 |  |
Customer accounts receivable - wastewater [Member] |  |  |  |  |  |  |
Summary of changes in entity's accounts receivable [Abstract] |  |  |  |  |  |  |
Gross accounts receivable |  |  |  | 1,717,000 | 209,000 |  |
Miscellaneous accounts receivable [Member] |  |  |  |  |  |  |
Summary of changes in entity's accounts receivable [Abstract] |  |  |  |  |  |  |
Gross accounts receivable |  |  |  | 699,000 | 402,000 |  |
CIAC receivable [Member] |  |  |  |  |  |  |
Summary of changes in entity's accounts receivable [Abstract] |  |  |  |  |  |  |
Gross accounts receivable |  |  |  | $ 1,901,000 | $ 992,000 |  |
Class A Stock [Member] | 2015 Equity Compensation Plan [Member] |  |  |  |  |  |  |
Stock Compensation Plans [Abstract] |  |  |  |  |  |  |
Number of share authorize under equity compensation plan (in shares) |  |  |  |  |  |  | 331,500
Class A Stock [Member] | Restricted Stock [Member] |  |  |  |  |  |  |
Stock Compensation Plans [Abstract] |  |  |  |  |  |  |
Granted, restricted stock awards (in shares) | 5,000 | 5,000 | 5,000 |  |  |  |
Fair market value (in dollars per share) | $ 35.01 | $ 36.11 | $ 38.51 |  |  |  |

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