Regulatory Matters (Details 5) - GSWC - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Regulatory matters:
Total	$ 132,696	$ 125,704
Pension Costs and Other Postretirement Benefit Costs [Member]
Regulatory matters:
Regulatory asset	19,800
Total	21,996	43,426
Pension Costs and Other Postretirement Benefit Costs [Member] | Two-way pension balancing account
Regulatory matters:
Regulatory asset	$ 2,200
Water Revenue Adjustment Mechanism Net of Modified Cost Balancing Account [Member]
Regulatory matters:
Commercial paper, term	90 days
Total	$ 45,171	9,369
Base revenue requirement adjustment mechanism
Regulatory matters:
Total	$ 3,714	7,761
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	$ 8,699	$ 9,109