Summary of Significant Accounting Policies: (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) customer registrant state shares	Mar. 31, 2022 USD ($) shares	Jan. 13, 2023 USD ($)	Dec. 31, 2022 USD ($)
Summary of significant accounting policies
Number of customers | customer	1,000,000
Number of States in which Entity Operates | state	9
Number of registrants filing combined report | registrant	2
Notes payable to banks	$ 175,500			$ 255,500
Exercise of stock options and other issuances of Common Shares (in shares) | shares	14,043	19,348
Term Maturity Date Extension	2 months
Parent Company
Summary of significant accounting policies
Net working capital	$ (168,000)
Parent Company | Syndicated Revolving Credit Facility
Summary of significant accounting policies
Notes payable to banks	$ 175,500
ASUS
Summary of significant accounting policies
Period of Fixed Price Contracts to Operate and Maintain Water Systems at Various Military Bases	50 years
Payments to affiliate for corporate office administrative and general costs	$ 1,500	$ 1,600
ASUS | Contracted services:
Summary of significant accounting policies
Period of Fixed Price Contracts to Operate and Maintain Water Systems at Various Military Bases	50 years
BVES
Summary of significant accounting policies
Payments to affiliate for corporate office administrative and general costs	$ 1,300	$ 794
Maximum borrowing capacity on line of credit	35,000
Incremental expansion of borrowing capacity	15,000
Notes Payable	$ 25,000
BVES | Electric:
Summary of significant accounting policies
Number of customers | customer	24,700
GSWC
Summary of significant accounting policies
Intercompany payable	$ 428			0
Net working capital	(87,900)
Intercompany note payable	$ 45,000			$ 0
Exercise of stock options and other issuances of Common Shares (in shares) | shares	1
Exercise of stock options and other issuances of Common Shares (in shares)	$ 10,000
Intercompany Borrowings Payment Term	24 months
GSWC | Unsecured Private Placement Notes
Summary of significant accounting policies
Debt Instrument, Face Amount			$ 130,000
GSWC | Water:
Summary of significant accounting policies
Number of customers | customer	263,400
Maximum | Parent Company | Revolving Credit Facility
Summary of significant accounting policies
Line of Credit Facility, Current Borrowing Capacity	$ 280,000