Regulatory Matters (Details) - USD ($)	1 Months Ended		12 Months Ended
	Oct. 31, 2005	Jul. 31, 2005	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Regulatory matters:
Regulatory Asset Not Accruing Carrying Costs			$ 56,300,000
Various refunds to customers
Regulatory matters:
Decrease in revenues requirement to reflect the newly adopted Cost of Capital for GSWC			961,000
Water Revenue Adjustment Mechanism [Member]
Regulatory matters:
Regulatory adjustment			9,400,000
Pension Costs and Other Postretirement Benefit Costs
Regulatory matters:
Regulatory Asset Not Accruing Carrying Costs			$ 36,200,000
General Rate Case Memorandum Accounts [Member]
Regulatory matters:
Total					$ 9,500,000
Cost of Capital, Proceeding for Water Regions [Member]
Regulatory matters:
Weighted Cost of Capital Percent			8.34%
Settlement Agreement Proposed Authorized Return on Equity Percentage			9.43%
GSWC
Regulatory matters:
Total			$ (28,340,000)	$ 2,042,000
GSWC | Revenue Subject to Refund for TCJA [Member]
Regulatory matters:
Total			(8,293,000)	0
GSWC | Various refunds to customers
Regulatory matters:
Total			(7,517,000)	(6,070,000)
GSWC | Renewables Portfolio Standard [Member]
Regulatory matters:
Provision for Other Losses			0
GSWC | Revenue Subject to Refund for TCJA [Member]
Regulatory matters:
Adjustments recorded to revalue deferred taxes as a result of the tax cut and job act of 2017 impact			7,100,000
GSWC | WRAM, net of MCBA
Regulatory matters:
Total			17,763,000	29,556,000
GSWC | Water Revenue Adjustment Mechanism [Member]
Regulatory matters:
Total			3,800,000
Water			0
GSWC | Costs deferred for future recovery on Aerojet case
Regulatory matters:
Total			9,516,000	10,656,000
Regulatory Asset Recovery Periods		20 years
GSWC | Pension Costs and Other Postretirement Benefit Costs
Regulatory matters:
Regulatory Assets			36,200,000
Total			33,124,000	33,019,000
GSWC | Gain (Loss) on Derivative Instruments [Member]
Regulatory matters:
Total			311,000	2,941,000
GSWC | Flow-through taxes, net
Regulatory matters:
Total			(15,300,000)	(17,700,000)
GSWC | Deferred Income Tax Charge [Member]
Regulatory matters:
Total			(81,465,000)	(83,231,000)
GSWC | Low income rate assistance balancing accounts
Regulatory matters:
Total			2,784,000	5,972,000
GSWC | Other regulatory assets, net
Regulatory matters:
Total			15,656,000	16,393,000
GSWC | General Rate Case Memorandum Accounts [Member]
Regulatory matters:
Total			$ 5,054,000	$ 10,522,000
GSWC | Cost of Capital, Proceeding for Water Regions [Member]
Regulatory matters:
Return on Equity Percentage			8.90%
Weighted Cost of Capital Percent			7.91%
Electric Service Utility Operations [Member] | Revenue Subject to Refund for TCJA [Member]
Regulatory matters:
Adjustments recorded to revalue deferred taxes as a result of the tax cut and job act of 2017 impact			$ 1,200,000
Electric Service Utility Operations [Member] | Pending General Rate Case [Member]
Regulatory matters:
Return on Equity Percentage			9.60%
Settlement Agreement Proposed Authorized Return on Equity Percentage			9.95%
Minimum | GSWC | General Rate Case Memorandum Accounts [Member]
Regulatory matters:
Regulatory Asset Recovery Periods			12 months
Maximum | GSWC | WRAM, net of MCBA
Regulatory matters:
Regulatory Asset Recovery Periods			24 months
Maximum | GSWC | Costs deferred for future recovery on Aerojet case
Regulatory matters:
Regulatory Asset Recovery Periods	20 years
Maximum | GSWC | General Rate Case Memorandum Accounts [Member]
Regulatory matters:
Regulatory Asset Recovery Periods			36 months
Under Collection in Two Way Pension Balancing Account [Member] | GSWC | Pension Costs and Other Postretirement Benefit Costs
Regulatory matters:
Regulatory adjustment			$ (3,034,000)
Regulatory Assets			$ 3,000,000