Regulatory Matters 5 (Details) - GSWC - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Regulatory matters:
Total	$ 2,042	$ 146,281
Pension Costs and Other Postretirement Benefit Costs
Regulatory matters:
Regulatory asset	34,700
Total	33,019	28,118
Pension Costs and Other Postretirement Benefit Costs | Two-way pension balancing account
Regulatory matters:
Regulatory asset	$ 1,700
Water Revenue Adjustment Mechanism Net of Modified Cost Balancing Account [Member]
Regulatory matters:
Commercial paper, term	90 days
Total	$ 29,556	47,340
Low income rate assistance balancing accounts
Regulatory matters:
Commercial paper, term	90 days
Discount percentage for qualified low-income water customers	15.00%
Discount percentage for qualified low-income electric customers	20.00%
Total	$ 5,972	$ 8,272