Regulatory Matters 5 (Details) - GSWC - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Regulatory matters:
Total	$ 146,281	$ 132,696
Pension Costs and Other Postretirement Benefit Costs
Regulatory matters:
Regulatory asset	26,800
Total	28,118	21,996
Pension Costs and Other Postretirement Benefit Costs | Two-way pension balancing account
Regulatory matters:
Regulatory asset	$ 1,300
Water Revenue Adjustment Mechanism Net of Modified Cost Balancing Account [Member]
Regulatory matters:
Commercial paper, term	90 days
Total	$ 47,340	45,171
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	$ 8,272	$ 8,699