Contingencies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) item
American States Utility Services | Contracted services:
Contingencies
Period of Fixed Price Contracts to Operate and Maintain Water Systems at Various Military Bases	50 years
Environmental Clean-Up and Remediation | GSWC
Contingencies
Amount spent in clean-up and remediation activities	$ 6.2
Amount paid by the State of California Underground Storage Tank Fund for clean-up and remediation of plant facilities	1.5
Accrued liability for the estimated additional cost to complete the clean-up at the site	$ 1.3
Number of Plant Sites | item	1