Regulatory Matters: (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Regulatory matters:
Regulatory asset not accruing carrying costs	$ 67,900
Other Liabilities, Current	17,451	$ 18,760
Pension and other post-retirement obligations
Regulatory matters:
Regulatory asset not accruing carrying costs	39,700
Derivative unrealized loss
Regulatory matters:
Regulatory asset not accruing carrying costs	5,700
GOLDEN STATE WATER COMPANY
Regulatory matters:
Regulatory assets	139,240	125,704
Other Liabilities, Current	17,223	18,659
GOLDEN STATE WATER COMPANY | Water Revenue Adjustment Mechanism, net of Modified Cost Balancing Account
Regulatory matters:
Regulatory Asset Amount Billed to Customers as Surcharges	96
Regulatory assets	28,542	9,369
GOLDEN STATE WATER COMPANY | Base Revenue Requirement Adjustment Mechanism
Regulatory matters:
Regulatory assets	5,668	7,761
GOLDEN STATE WATER COMPANY | Costs deferred for future recovery on Aerojet case
Regulatory matters:
Regulatory assets	13,220	13,629
GOLDEN STATE WATER COMPANY | Pension and other post-retirement obligations
Regulatory matters:
Regulatory assets	42,145	43,426
GOLDEN STATE WATER COMPANY | Derivative unrealized loss
Regulatory matters:
Regulatory assets	5,662	3,339
GOLDEN STATE WATER COMPANY | Flow-through taxes, net
Regulatory matters:
Regulatory assets	16,745	17,612
GOLDEN STATE WATER COMPANY | Low income rate assistance balancing accounts
Regulatory matters:
Regulatory assets	8,990	9,109
GOLDEN STATE WATER COMPANY | Other regulatory assets
Regulatory matters:
Regulatory assets	18,888	22,218
Other Liabilities, Current	3,800
Various refunds to customers | GOLDEN STATE WATER COMPANY
Regulatory matters:
Regulatory assets	$ (620)	$ (759)