Bank Debt (Details) $ in Thousands		12 Months Ended
	Jun. 28, 2023	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023 USD ($) unit	Dec. 31, 2022 USD ($)	Feb. 15, 2024 USD ($)	Nov. 06, 2023 USD ($)	Nov. 05, 2023 USD ($)	Jun. 27, 2023 USD ($)	Jun. 16, 2023 USD ($)	Jun. 15, 2023 USD ($)
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				$ 291,500	$ 22,000
Notes payable to bank				$ 42,000	255,500
BVES
Bank debt
Debt instrument, term				24 months
Incremental expansion of borrowing capacity										$ 25,000
Debt Instrument, Face Amount											$ 35,000
GSWC
Bank debt
Ratio of Indebtedness to Net Capital				0.4956
Note payable to bank, noncurrent				$ 150,000	0
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				$ 333,500	277,500
Average Amount Outstanding				243,355	226,556
Maximum Amount Outstanding				$ 333,500	$ 277,500
Weighted Average Annual Interest Rate (as a percent)				6.11%	2.55%
Short-term borrowing activities (excluding letters of credit)
Notes Payable				$ 333,500	$ 277,500
Weighted Average Annual Interest Rate (as a percent)				6.11%	2.55%
Average Amount Outstanding				$ 243,355	$ 226,556
Maximum Amount Outstanding				$ 333,500	$ 277,500
Revolving Credit Facility | BVES
Bank debt
Maximum borrowing capacity										$ 50,000
Interest coverage ratio				4.51
Total funded debt ratio				0.52
Notes payable to bank				$ 42,000
Revolving Credit Facility | BVES | Subsequent Event
Bank debt
Maximum borrowing capacity						$ 65,000
Revolving Credit Facility | GSWC
Bank debt
Incremental expansion of borrowing capacity				75,000
Debt issuance costs, line of credit arrangements, gross				$ 802
Total funded debt ratio				0.50
Note payable to bank, noncurrent				$ 150,000
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)				6.96%	5.89%
Short-term borrowing activities (excluding letters of credit)
Interest Rate at the end of the period (as a percent)				6.96%	5.89%
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)				6.33%	5.07%
Short-term borrowing activities (excluding letters of credit)
Interest Rate at the end of the period (as a percent)				6.33%	5.07%
Revolving Credit Facility | Minimum | BVES | Subsequent Event
Bank debt
Interest coverage ratio		4.5	3.0
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				141,500	$ 0
Notes payable to bank				$ 0	255,500
AWR | Maximum
Bank debt
Line of credit facility, current borrowing capacity									$ 280,000
AWR | Revolving Credit Facility
Bank debt
Total funded debt ratio				0.54
Note payable to bank, noncurrent				$ 141,500
Notes Payable				141,500	255,500
Average Amount Outstanding				156,533	213,758
Maximum Amount Outstanding				$ 257,500	$ 255,500
Interest Rate at the end of the period (as a percent)				6.45%	5.07%
Weighted Average Annual Interest Rate (as a percent)				5.92%	2.56%
Short-term borrowing activities (excluding letters of credit)
Notes Payable				$ 141,500	$ 255,500
Interest Rate at the end of the period (as a percent)				6.45%	5.07%
Weighted Average Annual Interest Rate (as a percent)				5.92%	2.56%
Average Amount Outstanding				$ 156,533	$ 213,758
Maximum Amount Outstanding				257,500	$ 255,500
Parent | Revolving Credit Facility
Bank debt
Debt issuance costs, line of credit arrangements, gross				$ 632