Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	$ 75,061	$ 69,507
GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	44,803	45,729
GSWC | Deferred Income Tax Charge
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	(69,257)	(70,189)
GSWC | Pension Costs and Other Postretirement Benefit Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	(4,824)	(4,867)
GSWC | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	(576)	(268)
BVES | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	(7,676)	(6,578)
Golden State Water Company and Bear Valley Electric Service Inc.
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	75,100
Regulatory liabilities not accruing carrying costs	(77,800)
Golden State Water Company and Bear Valley Electric Service Inc. | Deferred Income Tax Charge
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities not accruing carrying costs	(73,000)
Golden State Water Company and Bear Valley Electric Service Inc. | Pension Costs and Other Postretirement Benefit Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities not accruing carrying costs	(3,300)
Golden State Water Company and Bear Valley Electric Service Inc. | Other regulatory liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities not accruing carrying costs	(1,500)
2022/2023 general rate case memorandum accounts (unbilled revenue) | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	41,656	52,795
Water revenue adjustment mechanism, net of modified cost balancing account | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	44,092	41,545
Asset retirement obligations | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	7,375	7,099
Flowed-through deferred income taxes, net | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	8,919	3,190
Low income rate assistance balancing accounts | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	8,164	5,763
Derivative instrument memorandum account (Note 5) | BVES
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	8,320	2,360
Wildfire mitigation and other fire prevention related costs memorandum accounts | BVES
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	20,904	17,716
Electric Supply Cost Adjustment Mechanism | BVES
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	284	2,583
Other regulatory assets | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	9,254	10,661
Other regulatory assets | BVES
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory Assets	$ 8,426	$ 7,697