Regulatory Matters - Narrative (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)
Regulatory matters:
Regulatory asset not accruing carrying costs	$ (62,600,000)	$ (62,600,000)
Regulatory asset amount billed to customers as surcharges		$ 0
GSWC
Regulatory matters:
Number of unresolved issues for 2022-2024 water General Rate Case	3	3
Regulatory asset-CEMA	$ 5,600,000	$ 5,600,000
Relief funding	9,500,000	9,500,000
GSWC | Cost of capital proceeding
Regulatory matters:
Revenue impact due to lower cost of debt	1,700,000	3,100,000
BVESI
Regulatory matters:
Regulatory asset-CEMA	652,000	652,000
Relief funding	321,000	321,000
Regulatory Asset -incremental vegetation management costs	6,900,000	6,900,000
Regulatory asset-Wildfire mitigation Plans ( WMP)	3,500,000	3,500,000
Regulatory asset CEMA - Storm	449,000	449,000
Excess deferred income taxes
Regulatory matters:
Regulatory asset not accruing carrying costs	(76,400,000)	(76,400,000)
Flow-through taxes, net
Regulatory matters:
Regulatory asset not accruing carrying costs	(4,700,000)	(4,700,000)
Pensions and other post-retirement obligations (Note 8)
Regulatory matters:
Regulatory asset not accruing carrying costs	(25,300,000)	(25,300,000)
Derivative unrealized gain (Note 5)
Regulatory matters:
Regulatory asset not accruing carrying costs	$ (8,100,000)	(8,100,000)
Water Revenue Adjustment Mechanism and Modified Cost Balancing Account
Regulatory matters:
Increase (decrease) in other regulatory assets		$ 13,100,000
Regulatory asset recovery periods		24 months
Water Revenue Adjustment Mechanism and Modified Cost Balancing Account | GSWC
Regulatory matters:
Commercial paper, term		90 days