LONG-TERM DEBT (Details) (USD $)	0 Months Ended	12 Months Ended
	Oct. 04, 2011	Dec. 31, 2014	Dec. 31, 2013
Long-term debt
Total long-term debt		$ 425,840,000	$ 434,050,000
Current maturities of long-term debt		6,607,000	7,908,000
Long-term debt, less current maturities		419,233,000	426,142,000
Cal Water
Long-term debt
Current maturities of long-term debt		6,173,000	6,137,000
Long-term debt, less current maturities		417,884,000	424,854,000
Debt maturity period	15 years
Capital lease liability	9,200,000
First Mortgage
Long-term debt
Total long-term debt		408,109,000	413,664,000
First Mortgage Bonds, 5.500% due 2040
Long-term debt
Interest rate (as a percent)		5.50%	5.50%
Total long-term debt		100,000,000	100,000,000
First Mortgage Bonds, 5.500% due 2040 | Cal Water
Long-term debt
Interest rate (as a percent)		5.50%
First Mortgage Bonds, 5.875% due 2019
Long-term debt
Interest rate (as a percent)		5.875%	5.875%
Total long-term debt		100,000,000	100,000,000
First Mortgage Bonds, 5.875% due 2019 | Cal Water
Long-term debt
Interest rate (as a percent)		5.875%
First Mortgage Bonds AAA Series, due in 2025
Long-term debt
Interest rate (as a percent)		7.28%	7.28%
Total long-term debt		20,000,000	20,000,000
First Mortgage Bonds BBB Series, due in 2028
Long-term debt
Interest rate (as a percent)		6.77%	6.77%
Total long-term debt		20,000,000	20,000,000
First Mortgage Bonds CCC Series, Due 2030
Long-term debt
Interest rate (as a percent)		8.15%	8.15%
Total long-term debt		20,000,000	20,000,000
First Mortgage Bonds DDD Series, Due 2031
Long-term debt
Interest rate (as a percent)		7.13%	7.13%
Total long-term debt		20,000,000	20,000,000
First Mortgage Bonds EEE Series, Due 2032
Long-term debt
Interest rate (as a percent)		7.11%	7.11%
Total long-term debt		20,000,000	20,000,000
First Mortgage Bonds FFF Series, Due 2017
Long-term debt
Interest rate (as a percent)		5.90%	5.90%
Total long-term debt		20,000,000	20,000,000
First Mortgage Bonds GGG Series, Due 2022
Long-term debt
Interest rate (as a percent)		5.29%	5.29%
Total long-term debt		14,545,000	16,364,000
First Mortgage Bonds HHH Series, Due 2022
Long-term debt
Interest rate (as a percent)		5.29%	5.29%
Total long-term debt		14,546,000	16,364,000
First Mortgage Bonds III Series, Due 2023
Long-term debt
Interest rate (as a percent)		5.54%	5.54%
Total long-term debt		8,182,000	9,091,000
First Mortgage Bonds JJJ Series, Due 2018
Long-term debt
Interest rate (as a percent)		5.44%	5.44%
Total long-term debt		3,636,000	4,545,000
First Mortgage Bonds LLL Series, Due 2018
Long-term debt
Interest rate (as a percent)		5.48%	5.48%
Total long-term debt		10,000,000	10,000,000
First Mortgage Bonds OOO Series, Due 2031
Long-term debt
Interest rate (as a percent)		6.02%	6.02%
Total long-term debt		20,000,000	20,000,000
First Mortgage Bonds CC Series, Due 2020
Long-term debt
Interest rate (as a percent)		9.86%	9.86%
Total long-term debt		17,200,000	17,300,000
California Department of Water Resources Loans
Long-term debt
Interest rate, low end of range (as a percent)		2.60%	2.60%
Interest rate, high end of range (as a percent)		8.00%	8.00%
Total long-term debt		7,212,000	8,008,000
Other Long-term Debt
Long-term debt
Total long-term debt		$ 10,519,000	$ 12,378,000