Regulatory Matters - Narrative (Details)	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Asset Not Accruing Carrying Costs	$ 85,000,000
Net regulatory assets	(25,454,000)	$ (22,796,000)
GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	$ (26,574,000)	(24,082,000)
Number of unresolved issues for 2022-2024 water General Rate Case	3
Regulatory Asset CEMA	$ 3,500,000
GSWC | Cost of capital proceeding
Schedule of Regulatory Assets and Liabilities [Line Items]
Revenue impact due to lower cost of debt	6,400,000
BVESI
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Asset CEMA	497,000
Approval amount for the relief funding	473,000
Incremental vegetation management costs	8,700,000
Regulatory Asset Wildfire Mitigation Plans WMP	4,300,000
Excess deferred income taxes (Note 11)
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	75,700,000
Excess deferred income taxes (Note 11) | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	(71,870,000)	(73,000,000)
Flow-through taxes, net (Note 11)
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	(1,100,000)
Flow-through taxes, net (Note 11) | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	(1,134,000)	(5,552,000)
Pensions and other post-retirement obligations (Note 12)
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Asset Not Accruing Carrying Costs	2,200,000
Pensions and other post-retirement obligations (Note 12) | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	738,000	25,212,000
Regulatory Assets	2,200,000
Pensions and other post-retirement obligations (Note 12) | Golden State Water Company and Bear Valley Electric Service, Inc. | Under Collection in Two Way Pension Balancing Account
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	1,500,000
Pensions and other post-retirement obligations (Note 12) | BVESI | Under Collection in Two Way Pension Balancing Account
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	496,000
Derivative instrument memorandum account (Note 5)
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	(11,800,000)
Derivative instrument memorandum account (Note 5) | BVESI
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	(11,847,000)	(4,441,000)
Water Revenue Adjustment Mechanism, net of the Modified Cost Balancing Account | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	$ 31,803,000	13,326,000
Commercial paper, term	90 days
Amount billed to customers as surcharges	$ 4,400,000
Water Revenue Adjustment Mechanism, net of the Modified Cost Balancing Account | GSWC | Maximum
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Asset Recovery Periods	24 months
Water Revenue Adjustment Mechanism
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory adjustment	$ 22,800,000
Water Revenue Adjustment Mechanism | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	17,200,000
Deferred Revenues	0
Modified Cost Balancing Account | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	14,600,000
COVID-19 memorandum account | GSWC
Schedule of Regulatory Assets and Liabilities [Line Items]
Net regulatory assets	3,478,000	$ 1,663,000
Approval amount for the relief funding	$ 9,500,000