Regulatory Matters 3 (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Regulatory matters:
Other Liabilities, Current	$ 15,109	$ 11,297
GSWC
Regulatory matters:
Under (over) collection	2,042	146,281
Other Liabilities, Current	14,705	10,925
Other Regulatory Assets Net [Member] | GSWC
Regulatory matters:
Under (over) collection	14,875	17,633
Low income rate assistance balancing accounts | GSWC
Regulatory matters:
Under (over) collection	5,972	8,272
Pension Costs and Other Postretirement Benefit Costs | GSWC
Regulatory matters:
Regulatory asset authorized under settlement	34,700
Under (over) collection	33,019	$ 28,118
Two-way pension balancing account | Pension Costs and Other Postretirement Benefit Costs | GSWC
Regulatory matters:
Regulatory asset authorized under settlement	1,700
Two-way pension balancing account | Purchase, production, distribution and sale of water | Pension Costs and Other Postretirement Benefit Costs | GSWC
Regulatory matters:
Regulatory asset authorized under settlement	(588)
Two-way pension balancing account | Electric | Pension Costs and Other Postretirement Benefit Costs | GSWC
Regulatory matters:
Regulatory asset authorized under settlement	$ (1,060)