Regulatory Matters - Narrative (Details)		3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 29, 2023	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022	Apr. 10, 2023 USD ($)
Regulatory matters:
Regulatory Asset Not Accruing Carrying Costs		$ 73,700,000			$ 73,700,000
Net regulatory Assets		56,310,000			56,310,000	$ (25,454,000)
Regulatory asset amount billed to customers as surcharges					$ 0
Cost of capital proceeding
Regulatory matters:
Adjustment To Return On Equity, If More Than 100 Basis Point Change					0.5
Threshold percentage of Moody's average bond rate used adjusting return on equity and rate of return on rate base, Increase(Decrease)					0.0100
GSWC
Regulatory matters:
Net regulatory Assets		44,805,000			$ 44,805,000	(26,574,000)
Public Utilities Approved Debt Capital Structure, Percentage Previously Authorized					6.60%
Public Utilities, Approved Return on Equity, Percentage Previously Authorized					8.90%
Regulatory asset-CEMA		3,500,000			$ 3,500,000
Public Utilities, Approved Equity Capital Structure, Percentage	57.00%
Public Utilities, Approved Debt Capital Structure, Percentage	43.00%
GSWC | Cost of capital proceeding
Regulatory matters:
Public Utilities, Approved Debt Capital Structure in May 2021 Cost of Capital Application, Percentage					5.10%
Public Utilities, Approved Return On Equity in May 2021 Cost of Capital Application, Percentage					8.85%
Term for the cost of capital proceeding					3 years
Revenue impact due to lower cost of debt		9,300,000	$ 2,900,000		$ 6,400,000
Triggers for the WCMA adjustment, Impact of 103 Basis Point Increase in Moody's Rate, Percent							0.01028
GSWC | Cost of capital proceeding | Subsequent Event [Member]
Regulatory matters:
Public Utilities, Requested Return on Equity, Percentage				9.36%
BVES
Regulatory matters:
Regulatory asset-CEMA		500,000			500,000			$ 0
Regulatory Asset -incremental vegetation management costs		10,100,000			10,100,000
Regulatory asset-Wildfire mitigation Plans ( WMP)		5,000,000			5,000,000
Regulatory asset CEMA - Storm		1,300,000			$ 1,300,000
2022/2023 general rate case memorandum accounts (unbilled revenue)
Regulatory matters:
Period to file GSWC's general rate memorandum accounts					90 days
2022/2023 general rate case memorandum accounts (unbilled revenue) | GSWC
Regulatory matters:
Net regulatory Assets		50,345,000			$ 50,345,000	0
Regulatory asset recovery periods					36 months
Water revenue adjustment mechanism, net of modified cost balancing account
Regulatory matters:
Increase (decrease) in other regulatory assets					$ 22,200,000	(9,800,000)
Regulatory asset recovery periods					24 months
Water revenue adjustment mechanism, net of modified cost balancing account | GSWC
Regulatory matters:
Net regulatory Assets		39,006,000			$ 39,006,000	31,803,000
Commercial paper, term					90 days
COVID-19 memorandum accounts | GSWC
Regulatory matters:
Net regulatory Assets		3,543,000			$ 3,543,000	3,478,000
Excess deferred income taxes
Regulatory matters:
Regulatory Asset Not Accruing Carrying Costs		74,900,000			74,900,000
Excess deferred income taxes | GSWC
Regulatory matters:
Net regulatory Assets		(70,967,000)			(70,967,000)	(71,870,000)
Derivative instrument memorandum account (Note 5)
Regulatory matters:
Regulatory Asset Not Accruing Carrying Costs		4,700,000			4,700,000
Derivative instrument memorandum account (Note 5) | BVES
Regulatory matters:
Net regulatory Assets		(4,657,000)			(4,657,000)	$ (11,847,000)
Pension Costs and Other Postretirement Benefit Costs [Member]
Regulatory matters:
Regulatory Asset Not Accruing Carrying Costs		2,400,000			2,400,000
Modified Cost Balancing account ("MCBA") | GSWC
Regulatory matters:
Net regulatory Assets		(4,400,000)			(4,400,000)
Water Revenue Adjustment Mechanism ("WRAM") | GSWC
Regulatory matters:
Net regulatory Assets		$ 43,400,000			$ 43,400,000