Employee Benefit Plans Employee Benefit Plans 5 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee benefit plans
Regulatory asset authorized under settlement	$ 2,700
Pension Benefits
Employee benefit plans
Regulatory adjustment	593	$ 0	$ (465)
GSWC | Pension Benefits
Employee benefit plans
Regulatory adjustment		$ 1,700	$ 583
Pension Costs and Other Postretirement Benefit Costs | GSWC
Employee benefit plans
Regulatory asset authorized under settlement	43,400
Two-way pension balancing account | Pension Costs and Other Postretirement Benefit Costs | GSWC
Employee benefit plans
Regulatory adjustment	$ (2,700)