LONG-TERM DEBT - Narrative (Details) - USD ($) $ in Thousands	May 11, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2011
Long-term debt
Operating lease, liability		$ 15,403	$ 15,625
Cal Water
Long-term debt
Operating lease term				15 years
Operating lease, liability		$ 3,900	$ 4,600
Secured Debt
Long-term debt
Debt issued	$ 280,000
Secured Debt | Series ZZZ Mortgage Bonds
Long-term debt
Debt issued	$ 130,000
Interest rate margin (as a percent)	2.87%
Secured Debt | Series 1 Mortgage Bonds
Long-term debt
Debt issued	$ 150,000
Interest rate margin (as a percent)	3.02%