Summary of Significant Accounting Policies: (Details)		3 Months Ended			6 Months Ended
	Jun. 28, 2023 USD ($)	Jun. 30, 2023 USD ($) state	Mar. 31, 2023 USD ($) shares	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) customer state registrant shares	Jun. 30, 2022 USD ($) 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			9
Number of registrants filing combined report | registrant					2
Issuances of Common Shares under stock-based compensation plans | shares					14,358	19,742
Debt instrument term					5 years
Incremental expansion of borrowing capacity		$ 75,000,000			$ 75,000,000
Notes payable to banks		243,000,000			243,000,000			$ 22,000,000
Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Line of credit arrangements		530,000			530,000
Repayments of Lines of Credit	$ 280,000,000
Letter of Credit
Summary of significant accounting policies
Maximum borrowing capacity on line of credit		10,000,000			10,000,000
Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Notes payable to banks		135,000,000			$ 135,000,000
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		1,200,000		$ 1,100,000	$ 2,700,000	$ 2,700,000
BVES
Summary of significant accounting policies
Payments to affiliate for corporate office administrative and general costs		745,000		$ 592,000	2,100,000	$ 1,400,000
Current borrowing capacity		35,000,000			35,000,000
Incremental expansion of borrowing capacity		25,000,000			25,000,000
Maximum borrowing capacity on line of credit		50,000,000			50,000,000
BVES | Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Notes payable to banks		30,000,000			$ 30,000,000
BVES | Electric:
Summary of significant accounting policies
Number of customers | customer					24,700
GSWC
Summary of significant accounting policies
Issuances of Common Shares under stock-based compensation plans | shares			1
Issuance of common share to parent			$ 10,000,000
Intercompany borrowings payment term					24 months
Incremental expansion of borrowing capacity		75,000,000			$ 75,000,000
Notes payable to banks		0			0			$ 129,000,000
GSWC | Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Line of credit arrangements		702,000			702,000
GSWC | Letter of Credit
Summary of significant accounting policies
Maximum borrowing capacity on line of credit		20,000,000			20,000,000
GSWC | Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Notes payable to banks		78,000,000			$ 78,000,000
GSWC | Unsecured Private Placement Notes
Summary of significant accounting policies
Face amount of debt							$ 130,000,000
GSWC | Water:
Summary of significant accounting policies
Number of customers | customer					263,600
Maximum | Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Current borrowing capacity		$ 150,000,000			$ 150,000,000
Ratio of Indebtedness to Net Capital		0.65			0.65
Maximum | GSWC | Syndicated Revolving Credit Facility member [Member]
Summary of significant accounting policies
Current borrowing capacity		$ 200,000,000			$ 200,000,000
Ratio of Indebtedness to Net Capital		0.65			0.65