Leases Lease- additional information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Leases [Abstract]
Operating lease liabilities	$ 1,849	$ 0
Operating lease liabilities	11,739	0
Operating lease right-of-use assets	13,168	0		$ 7,600
Debt Instrument [Line Items]
Notes Payable to Bank	205,000
Operating Lease, Expense	2,800	$ 2,500	$ 2,400
9.56% notes due 2031
Debt Instrument [Line Items]
Notes Payable to Bank	$ 28,000
Interest rate (as a percent)	9.56%	9.56%
Golden State Water Company [Member]
Leases [Abstract]
Operating lease liabilities	$ 1,612	$ 0
Operating lease liabilities	11,588	0
Operating lease right-of-use assets	$ 12,745	$ 0
Debt Instrument [Line Items]
Ratio of Indebtedness to Net Capital	0.4445
Golden State Water Company [Member] | 9.56% notes due 2031
Debt Instrument [Line Items]
Interest rate (as a percent)	9.56%	9.56%
Golden State Water Company [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Indebtedness to Net Capital	0.6667