LONG-TERM DEBT - Long term Debt Outstanding (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Long-term debt
Unamortized debt issuance costs	$ (5,112)	$ (5,339)
Total long-term debt	1,055,797	1,060,986
Current maturities of long-term debt, net	3,310	5,192
Long-term debt, net	1,052,487	1,055,794
First Mortgage
Long-term debt
Long-term debt	$ 1,050,909	1,055,454
First Mortgage Bonds, ZZZ Series, Due 2051
Long-term debt
Interest rate	2.87%
Long-term debt	$ 130,000	130,000
Frist Mortgage Bonds, Series 1, Due 2061
Long-term debt
Interest rate	3.02%
Long-term debt	$ 150,000	150,000
First Mortgage Bonds YYY Series Due 2059
Long-term debt
Interest rate	4.17%
Long-term debt	$ 200,000	200,000
First Mortgage Bonds WWW Series Due 2049
Long-term debt
Interest rate	4.07%
Long-term debt	$ 100,000	100,000
First Mortgage Bonds VVV Series Due 2029
Long-term debt
Interest rate	3.40%
Long-term debt	$ 100,000	100,000
First Mortgage Bonds TTT Series Due 2056
Long-term debt
Interest rate	4.61%
Long-term debt	$ 10,000	10,000
First Mortgage Bonds SSS Series Due 2046
Long-term debt
Interest rate	4.41%
Long-term debt	$ 40,000	40,000
First Mortgage Bonds QQQ Series Due 2025
Long-term debt
Interest rate	3.33%
Long-term debt	$ 50,000	50,000
First Mortgage Bonds RRR Series Due 2045
Long-term debt
Interest rate	4.31%
Long-term debt	$ 50,000	50,000
First Mortgage Bonds PPP Series, due 2040
Long-term debt
Interest rate	5.50%
Long-term debt	$ 100,000	100,000
First Mortgage Bonds AAA Series, due in 2025
Long-term debt
Interest rate	7.28%
Long-term debt	$ 20,000	20,000
First Mortgage Bonds BBB Series, due in 2028
Long-term debt
Interest rate	6.77%
Long-term debt	$ 20,000	20,000
First Mortgage Bonds CCC Series, Due 2030
Long-term debt
Interest rate	8.15%
Long-term debt	$ 20,000	20,000
First Mortgage Bonds DDD Series, Due 2031
Long-term debt
Interest rate	7.13%
Long-term debt	$ 20,000	20,000
First Mortgage Bonds EEE Series, Due 2032
Long-term debt
Interest rate	7.11%
Long-term debt	$ 20,000	20,000
First Mortgage Bonds GGG Series, Due 2022
Long-term debt
Interest rate	5.29%
Long-term debt	$ 0	1,818
First Mortgage Bonds HHH Series, Due 2022
Long-term debt
Interest rate	5.29%
Long-term debt	$ 0	1,818
First Mortgage Bonds III Series, Due 2023
Long-term debt
Interest rate	5.54%
Long-term debt	$ 909	1,818
First Mortgage Bonds OOO Series, Due 2031
Long-term debt
Interest rate	6.02%
Long-term debt	$ 20,000	20,000
California Department of Water Resources Loans
Long-term debt
Long-term debt	$ 4,515	4,832
California Department of Water Resources Loans | Minimum
Long-term debt
Interest rate	1.48%
California Department of Water Resources Loans | Maximum
Long-term debt
Interest rate	1.69%
Other Long-term Debt
Long-term debt
Long-term debt	$ 5,485	$ 6,039