DEBT, Long-Term Debt (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Long-term debt consists of [Abstract]
Long term debt	$ 144,850	$ 144,090
Less: current maturities (principal amount)	1,591	1,757
Total long-term debt	143,259	142,333
Payments of principal amounts due during the next five years and thereafter [Abstract]
2020	1,591
2021	1,701
2022	1,638
2023	1,603
2024	1,563
Thereafter	136,754
Promissory Note [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 10,888	11,279
Interest rate, stated percentage	5.12%
Maturity date	Dec. 30, 2028
First Mortgage Bonds [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 127,200	127,800
Payments of principal amounts due during the next five years and thereafter [Abstract]
2020	600
2021	600
2022	600
2023	600
2024	600
Thereafter	124,200
First Mortgage Bonds [Member] \| Series R [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 25,000	25,000
Interest rate, stated percentage	5.96%
Maturity date	Dec. 31, 2028
First Mortgage Bonds [Member] \| Series S [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 7,200	7,800
Interest rate, stated percentage	4.45%
Maturity date	Dec. 31, 2033
First Mortgage Bonds [Member] \| Series T [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 40,000	40,000
Interest rate, stated percentage	4.24%
Maturity date	Dec. 20, 2036
First Mortgage Bonds [Member] \| Series U [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 25,000	25,000
Interest rate, stated percentage	4.71%
Maturity date	Jan. 31, 2038
First Mortgage Bonds [Member] \| Series V [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 30,000	30,000
Interest rate, stated percentage	4.42%
Maturity date	Oct. 31, 2049
State Revolving Fund Loans [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 6,762	5,011
Payments of principal amounts due during the next five years and thereafter [Abstract]
2020	580
2021	668
2022	584
2023	523
2024	458
Thereafter	3,949
State Revolving Fund Loans [Member] \| 4.48%, due 08/01/2021 [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 0	318
Interest rate, stated percentage	4.48%
Maturity date	Aug. 01, 2021
State Revolving Fund Loans [Member] \| 3.57%, due 09/01/2023 [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 200	294
Interest rate, stated percentage	3.57%
Maturity date	Sep. 01, 2023
State Revolving Fund Loans [Member] \| 3.64%, due 05/01/2025 [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 513	648
Interest rate, stated percentage	3.64%
Maturity date	May 01, 2025
State Revolving Fund Loans [Member] \| 3.41%, due 02/01/2031 [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 1,735	1,887
Interest rate, stated percentage	3.41%
Maturity date	Feb. 01, 2031
State Revolving Fund Loans [Member] \| 3.40%, due 07/01/2032 [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 1,729	1,864
Interest rate, stated percentage	3.40%
Maturity date	Jul. 01, 2032
State Revolving Fund Loans [Member] \| 1.187% due 11/01/2041 [Member]
Long-term debt consists of [Abstract]
Long term debt	$ 2,585	$ 0
Interest rate, stated percentage	1.187%
Maturity date	Nov. 01, 2041
State Revolving Fund Loans [Member] \| Promissory Note [Member]
Payments of principal amounts due during the next five years and thereafter [Abstract]
2020	$ 411
2021	433
2022	454
2023	480
2024	505
Thereafter	$ 8,605

Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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