Bank Debt (Details) $ in Thousands		12 Months Ended
	Jun. 28, 2023	Dec. 31, 2025	Dec. 31, 2024 USD ($) unit	Dec. 31, 2023 USD ($)	Feb. 12, 2025 USD ($)	Aug. 01, 2024 USD ($)	Feb. 15, 2024 USD ($)	Nov. 06, 2023 USD ($)	Nov. 05, 2023 USD ($)	Jun. 27, 2023 USD ($)	Jan. 13, 2023 USD ($)
Bank debt
Number of credit facilities | unit			3
Debt instrument, term	5 years
Line of credit facility, current borrowing capacity								$ 165,000
Incremental expansion of borrowing capacity									$ 75,000
Note payable to bank, noncurrent			$ 165,000	$ 291,500
BVES
Bank debt
Debt instrument, term			24 months
BVES | Subsequent Event | Debt due Feb 2030
Bank debt
Debt Instrument, Face Amount					$ 50,000
BVES | Financing Applications
Bank debt
Regulatory Rate Case Filings Requested Authorization For Debt And Equity Issuance Amount						$ 120,000
GSWC
Bank debt
Debt instrument, term			24 months
Ratio of indebtedness to net capital			0.4754
Note payable to bank, noncurrent			$ 0	150,000
Debt Instrument, Face Amount											$ 130,000
Maximum | GSWC
Bank debt
Ratio of indebtedness to net capital			0.6667
Revolving Credit Facility
Bank debt
Line of credit facility, current borrowing capacity									$ 150,000
Notes Payable			$ 289,000	333,500
Average Amount Outstanding			$ 315,811	$ 243,355
Weighted Average Annual Interest Rate (as a percent)			6.29%	6.11%
Maximum Amount Outstanding			$ 372,500	$ 333,500
Revolving Credit Facility | BVES
Bank debt
Debt instrument, term			5 years
Maximum borrowing capacity							$ 65,000
Interest coverage ratio			4.60
Total funded debt ratio			0.44
Line of credit facility, accordion feature, increase limit							$ 10,000
Note payable to bank, noncurrent			$ 45,000
Revolving Credit Facility | GSWC
Bank debt
Debt instrument, term			5 years
Incremental expansion of borrowing capacity			$ 75,000
Debt issuance costs, line of credit arrangements, gross			$ 800
Total funded debt ratio			0.48
Note payable to bank, noncurrent			$ 124,000
Revolving Credit Facility | Maximum
Bank debt
Ratio of indebtedness to net capital			0.65
Interest Rate at the end of the period (as a percent)			5.94%	6.96%
Revolving Credit Facility | Maximum | GSWC
Bank debt
Line of credit facility, current borrowing capacity			$ 200,000
Revolving Credit Facility | Minimum
Bank debt
Interest Rate at the end of the period (as a percent)			5.33%	6.33%
Revolving Credit Facility | Minimum | BVES
Bank debt
Interest coverage ratio			3.0
Revolving Credit Facility | Minimum | BVES | Subsequent Event
Bank debt
Interest coverage ratio		4.5
Letters of credit
Bank debt
Maximum borrowing capacity								$ 10,000
Letters of credit | GSWC
Bank debt
Maximum borrowing capacity			$ 20,000
AWR
Bank debt
Note payable to bank, noncurrent			$ 120,000	$ 141,500
AWR | Maximum
Bank debt
Line of credit facility, current borrowing capacity										$ 280,000
AWR | Revolving Credit Facility
Bank debt
Debt instrument, term			5 years
Debt issuance costs, line of credit arrangements, gross			$ 600
Total funded debt ratio			0.51
Note payable to bank, noncurrent			$ 120,000
Notes Payable			120,000	141,500
Average Amount Outstanding			$ 122,896	$ 156,533
Interest Rate at the end of the period (as a percent)			5.44%	6.45%
Weighted Average Annual Interest Rate (as a percent)			6.29%	5.92%
Maximum Amount Outstanding			$ 145,500	$ 257,500