Regulatory Matters: (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Apr. 08, 2019	Dec. 31, 2018
Regulatory matters:
Regulatory asset not accruing carrying costs	$ 56,000,000
Asset Impairment Charges	0
Pension and other post-retirement obligations
Regulatory matters:
Regulatory asset not accruing carrying costs	35,700,000
GOLDEN STATE WATER COMPANY
Regulatory matters:
Regulatory assets	(23,726,000)			$ (28,340,000)
GOLDEN STATE WATER COMPANY | Tax Cuts and Jobs Act (Tax Act) memorandum accounts
Regulatory matters:
Regulatory assets	(9,036,000)			(8,293,000)
GOLDEN STATE WATER COMPANY | Various refunds to customers
Regulatory matters:
Regulatory assets	(8,914,000)			(7,517,000)
GOLDEN STATE WATER COMPANY | Water Revenue Adjustment Mechanism and Modified Cost Balancing Account
Regulatory matters:
Amount billed to customers as surcharges	2,800,000	$ 4,200,000
Regulatory assets	24,998,000			17,763,000
GOLDEN STATE WATER COMPANY | Costs deferred for future recovery on Aerojet case
Regulatory matters:
Regulatory assets	9,397,000			9,516,000
GOLDEN STATE WATER COMPANY | Pension and other post-retirement obligations
Regulatory matters:
Regulatory assets	32,606,000			33,124,000
GOLDEN STATE WATER COMPANY | Derivative unrealized loss
Regulatory matters:
Regulatory assets	336,000			311,000
GOLDEN STATE WATER COMPANY | Low income rate assistance balancing accounts
Regulatory matters:
Regulatory assets	2,505,000			2,784,000
GOLDEN STATE WATER COMPANY | General Rate Case Memorandum Accounts
Regulatory matters:
Regulatory assets	3,956,000			5,054,000
GOLDEN STATE WATER COMPANY | Deferred Income Tax Charge
Regulatory matters:
Regulatory assets	(80,930,000)			(81,465,000)
GOLDEN STATE WATER COMPANY | Flow-through taxes, net
Regulatory matters:
Regulatory assets	(14,859,000)			(15,273,000)
GOLDEN STATE WATER COMPANY | Other Regulatory Assets Net [Member]
Regulatory matters:
Regulatory assets	16,215,000			$ 15,656,000
GOLDEN STATE WATER COMPANY | Water Revenue Adjustment Mechanism [Member]
Regulatory matters:
Regulatory assets	$ 10,100,000
Electric Service Utility Operations | GOLDEN STATE WATER COMPANY
Regulatory matters:
Return on Equity Percentage	9.95%
Electric Service Utility Operations | GOLDEN STATE WATER COMPANY | Pending General Rate Case [Member]
Regulatory matters:
Settlement Agreement Proposed Authorized Return on Equity Percentage	9.60%
Subsequent Event [Member] | GOLDEN STATE WATER COMPANY | Deferred Project Costs [Member]
Regulatory matters:
Regulatory assets			$ 20,400,000