Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Loss Contingencies [Line Items]
Amount spent in clean-up and remediation activities [Abstract]	$ 1,500
Utility plant	1,325,502	$ 1,296,310	$ 1,218,830
Accounts receivable	17,485	23,395
Total Assets	1,526,097	1,501,433	$ 1,423,664
Advances for construction	(66,185)	(66,305)
Contributions in aid of construction - net	125,530	124,385
GOLDEN STATE WATER COMPANY
Loss Contingencies [Line Items]
Utility plant	1,309,664	1,281,092
Accounts receivable	17,485	23,395
Regulatory assets	(23,726)	(28,340)
Total Assets	1,410,681	1,389,222
Advances for construction	(66,185)	(66,305)
Contributions in aid of construction - net	125,530	$ 124,385
Environmental Clean-Up and Remediation | GOLDEN STATE WATER COMPANY
Loss Contingencies [Line Items]
Environmental Remediation Expense	6,200
Accrued liability for the estimated additional cost to complete the clean-up at the site	$ 1,300