Revenues Contract assets and Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Contract with Customer, Asset and Liability [Line Items]
Contract with Customer, Liability, Revenue Recognized	$ 10,900
Revenue, Remaining Performance Obligation, Amount	3,200,000
American States Utility Services [Member]
Contract with Customer, Asset and Liability [Line Items]
Unbilled Contracts Receivable	14,924	$ 10,467
Government Contract Receivable	74,670	64,819
Contract assets	10,257	15,631
Contract liabilities	$ 1,800	$ 11,167
Minimum | American States Utility Services [Member]
Contract with Customer, Asset and Liability [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	34 years
Maximum | American States Utility Services [Member]
Contract with Customer, Asset and Liability [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	48 years
Contracted services: | American States Utility Services [Member]
Contract with Customer, Asset and Liability [Line Items]
Period of Fixed Price Contracts to Operate and Maintain Water Systems at Various Military Bases	50 years
Revenue, Performance Obligation, Description of Payment Terms	5