Regulatory Matters - Narrative (Details)		1 Months Ended			3 Months Ended	12 Months Ended
	Jul. 31, 2023	Dec. 31, 2022 USD ($)	Feb. 28, 2022 USD ($)	Jan. 31, 2022 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2024	Dec. 31, 2023 USD ($)	Sep. 30, 2023	Dec. 31, 2022 USD ($)
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Asset Not Accruing Carrying Costs							$ 68,400,000
Total		$ (25,454,000)					$ 69,507,000		$ (25,454,000)
Cost of capital proceeding
Schedule of Regulatory Assets and Liabilities [Line Items]
Public Utilities, Approved Debt Capital Structure in May 2021 Cost of Capital Application, Percentage							5.10%
Public Utilities Approved Debt Capital Structure, Percentage Previously Authorized							6.60%
Public Utilities, Approved Return On Equity in May 2021 Cost of Capital Application, Percentage							0.0885
Public Utilities, Approved Return on Equity, Percentage, Previously Authorized							8.90%
Term for the cost of capital proceeding							3 years
Threshold percentage of Moody's average bond rate used adjusting return on equity and rate of return on rate base, Increase(Decrease)							0.0100
Triggers for the WCMA adjustment, Impact of 102.8 Basis Point Increase in Moody's Rate, Percent							0.010280
Public Utilities, Requested Return on Equity, Percentage	9.36%
Triggers for the WCMA adjustment, Impact of 139.7 Basis Point Increase in Moody's Rate, Percent								0.013970
Adjustment To Return On Equity, If More Than 100 Basis Point Change							0.5
Cost of capital proceeding | Subsequent Event
Schedule of Regulatory Assets and Liabilities [Line Items]
Public Utilities, Requested Return on Equity, Percentage						10.06%
GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		(26,574,000)					$ 45,729,000		(26,574,000)
Public Utilities, Approved Equity Capital Structure, Percentage							57.00%
Public Utilities, Approved Debt Capital Structure, Percentage							43.00%
Revenue impact due to lower cost of debt							$ 6,400,000
Relief funding				$ 9,500,000			3,500,000		9,500,000
Regulatory Asset CEMA							$ 1,200,000
Discount Percentage For Qualified Low Income Water Customers							20.00%
BVES
Schedule of Regulatory Assets and Liabilities [Line Items]
Relief funding		152,000	$ 321,000						473,000
Regulatory Asset CEMA							$ 500,000
Discount Percentage For Qualified Low Income Water Customers							20.00%
Incremental vegetation management costs							$ 11,800,000
Regulatory Asset Wildfire Mitigation Plans WMP							5,900,000
Regulatory Asset CEMA -2023 Storm							$ 1,300,000
2022/2023 general rate case memorandum accounts (unbilled revenue)
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Asset, Amortization Period							36 months
2022/2023 general rate case memorandum accounts (unbilled revenue) | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		0					$ 52,795,000		0
Water revenue adjustment mechanism, net of the modified cost balancing account
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory adjustment					$ (9,800,000)
Water revenue adjustment mechanism, net of the modified cost balancing account | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		31,803,000					$ 41,545,000		31,803,000
Regulatory Asset, Amortization Period							24 months
Commercial paper, term							90 days
Pensions and other post-retirement obligations (Note 12)
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Asset Not Accruing Carrying Costs							$ 3,800,000
Pensions and other post-retirement obligations (Note 12) | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		738,000					(4,867,000)		738,000
Regulatory Assets							3,800,000
Pensions and other post-retirement obligations (Note 12) | GSWC | Under Collection in Two Way Pension Balancing Account
Schedule of Regulatory Assets and Liabilities [Line Items]
Total							1,100,000
Pensions and other post-retirement obligations (Note 12) | BVES | Under Collection in Two Way Pension Balancing Account
Schedule of Regulatory Assets and Liabilities [Line Items]
Total							277,000
Excess deferred income taxes (Note 11)
Schedule of Regulatory Assets and Liabilities [Line Items]
Total							74,000,000
Excess deferred income taxes (Note 11) | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		(71,870,000)					(70,189,000)		(71,870,000)
Flowed-through deferred income taxes, net (Note 11)
Schedule of Regulatory Assets and Liabilities [Line Items]
Total							4,300,000
Flowed-through deferred income taxes, net (Note 11) | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		(1,134,000)					3,190,000		(1,134,000)
Low income rate assistance balancing accounts | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		2,526,000					5,763,000		2,526,000
Low income rate assistance balancing accounts | Golden State Water Company and Bear Valley Electric Service, Inc.
Schedule of Regulatory Assets and Liabilities [Line Items]
Total							5,700,000
Derivative instrument memorandum account (Note 5)
Schedule of Regulatory Assets and Liabilities [Line Items]
Total							2,400,000
Derivative instrument memorandum account (Note 5) | BVES
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		(11,847,000)					2,360,000		(11,847,000)
Water Revenue Adjustment Mechanism
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory adjustment							30,100,000
Water Revenue Adjustment Mechanism | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total							43,900,000
Deferred Revenues							0
Modified Cost Balancing Account | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Total							2,400,000
Electric supply cost adjustment mechanism | BVES
Schedule of Regulatory Assets and Liabilities [Line Items]
Total		$ 3,627,000					2,583,000		$ 3,627,000
Amount billed to customers as surcharges							$ 1,900,000