Employee Benefit Plans Employee Benefit Plans 5 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Regulatory Adjustment:
Regulatory adjustment - over collection	$ (859)	$ (523)	$ (1,622)
GSWC | Pension Benefits
Regulatory Adjustment:
Regulatory adjustment - over collection	(859)	$ (523)	$ (1,600)
Pension Costs and Other Postretirement Benefit Costs | GSWC
Regulatory Adjustment:
Regulatory assets	26,800
Two-way pension balancing account | Pension Costs and Other Postretirement Benefit Costs | GSWC
Regulatory Adjustment:
Regulatory assets	$ 1,300