Summary of Significant Accounting Policies: (Details)		3 Months Ended		9 Months Ended
	Jul. 08, 2020 USD ($) Rate	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) registrant customer	Sep. 30, 2019 USD ($)	Jul. 15, 2020 USD ($)	Jul. 01, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Summary of significant accounting policies
Increase to provision		$ 871,000		$ 1,937,000
Nature of Operations:
Number of customers | customer				1,000,000
Number of States in which Entity Operates		9		9
Basis of Presentation [Abstract]
Number of registrants filing combined report | registrant				2
Related Party Transactions
Notes payable to bank		$ 92,000,000		$ 92,000,000					$ 200,000,000
Ratio of Indebtedness to EBITDA		8.00		8.00
Ratio of Indebtedness to Net Capital	0.6667
Note Payable 2.17 Percent Due 2030 [Member]
Related Party Transactions
Debt Instrument, Interest Rate, Stated Percentage	2.17%
Note Payable 2.9 Percent Due 2040 [Member]
Related Party Transactions
Debt Instrument, Interest Rate, Stated Percentage	2.90%
Parent Company [Member] | Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Incremental expansion of borrowing capacity								$ 35,000,000.0
Related Party Transactions
Incremental expansion of borrowing capacity								35,000,000.0
Notes Payable, Noncurrent		$ 89,000,000.0		$ 89,000,000.0
ASUS
Related Party Transactions
Payments to affiliate for corporate office administrative and general costs		1,200,000	$ 1,200,000	3,800,000	$ 3,500,000
Payments to affiliate for corporate office administrative and general costs		$ 1,200,000	$ 1,200,000	$ 3,800,000	$ 3,500,000
ASUS | Contracted Services
Nature of Operations:
Period of fixed price contracts to operate and maintain water systems at various military bases				50 years
Bear Valley Electric Service, Inc.
Summary of significant accounting policies
Incremental expansion of borrowing capacity							$ 15,000,000
Related Party Transactions
Payments to affiliate for corporate office administrative and general costs				$ 643,000
Maximum borrowing capacity on line of credit							35,000,000
Debt instrument term		3 years
Incremental expansion of borrowing capacity							$ 15,000,000
Payments to affiliate for corporate office administrative and general costs				$ 643,000
Bear Valley Electric Service, Inc. | Electric Service Utility Operations
Nature of Operations:
Number of customers | customer				24,500
Golden State Water Company
Summary of significant accounting policies
Increase to provision		$ 801,000		$ 1,867,000
Regulatory asset-CEMA		1,400,000		$ 1,400,000
Related Party Transactions
Related Party Transaction, Terms and Manner of Settlement				24
Due to Related Parties		$ 34,100,000		$ 34,100,000
Debt Instrument, Basis Spread on Variable Rate | Rate	0.50%
Golden State Water Company | Private Placement [Member]
Related Party Transactions
Debt Instrument, Face Amount	$ 160.0
Golden State Water Company | Note Payable 2.17 Percent Due 2030 [Member]
Related Party Transactions
Debt Instrument, Face Amount	85,000,000.0
Golden State Water Company | Note Payable 2.9 Percent Due 2040 [Member]
Related Party Transactions
Debt Instrument, Face Amount	$ 75,000,000.0
Golden State Water Company | Water Service Utility Operations
Nature of Operations:
Number of customers | customer				261,500
Maximum [Member] | Parent Company [Member] | Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Incremental expansion of borrowing capacity								260.0
Related Party Transactions
Incremental expansion of borrowing capacity								$ 260.0
Minimum [Member] | Parent Company [Member] | Revolving Credit Facility [Member]
Summary of significant accounting policies
Line of Credit Facility, Current Borrowing Capacity						$ 200,000,000.0