Bank Debt (Details) $ in Thousands		12 Months Ended
	Jan. 13, 2023 USD ($)	Dec. 31, 2022 USD ($) unit	Dec. 31, 2021 USD ($)	Apr. 22, 2022 USD ($)
Bank debt
Number of credit facilities | unit		2
Subsequent Event
Bank debt
Payment of long term loan with related parties	$ 124,000
Short-term borrowing activities (excluding letters of credit)
Payment of long term loan with related parties	$ 124,000
BVESI
Bank debt
Maximum borrowing capacity		$ 35,000
Debt instrument, term		24 years
Incremental expansion of borrowing capacity		$ 15,000
Notes Payable		22,000
GSWC
Bank debt
Maximum borrowing capacity		130,000
Long-term Debt
Bank debt
Balance Outstanding at December 31,		277,500	$ 205,500
Short-term borrowing activities (excluding letters of credit)
Balance Outstanding at December 31,		277,500	205,500
Short-term borrowing (excluding letters of credit)
Bank debt
Average Amount Outstanding		$ 226,556	$ 165,167
Weighted Average Annual Interest Rate (as a percent)		2.55%	1.05%
Maximum Amount Outstanding		$ 277,500	$ 205,500
Short-term borrowing activities (excluding letters of credit)
Average Amount Outstanding		$ 226,556	$ 165,167
Weighted Average Annual Interest Rate (as a percent)		2.55%	1.05%
Maximum Amount Outstanding		$ 277,500	$ 205,500
Short-term borrowing (excluding letters of credit) | Maximum
Bank debt
Interest Rate at the end of the period (as a percent)		5.89%	1.61%
Short-term borrowing activities (excluding letters of credit)
Interest Rate at the end of the period (as a percent)		5.89%	1.61%
Short-term borrowing (excluding letters of credit) | Minimum
Bank debt
Interest Rate at the end of the period (as a percent)		5.07%	0.78%
Short-term borrowing activities (excluding letters of credit)
Interest Rate at the end of the period (as a percent)		5.07%	0.78%
Syndicated revolving credit facility | BVESI
Bank debt
Interest coverage ratio		14.4
Total funded debt ratio		0.47
Short-term borrowing activities (excluding letters of credit)
Interest coverage ratio		14.4
Total funded debt ratio		0.47
Syndicated revolving credit facility | Maximum
Bank debt
Total funded debt ratio		0.65
Short-term borrowing activities (excluding letters of credit)
Total funded debt ratio		0.65
Syndicated revolving credit facility | Minimum
Bank debt
Interest coverage ratio		3.25
Short-term borrowing activities (excluding letters of credit)
Interest coverage ratio		3.25
Syndicated revolving credit facility | Minimum | BVESI
Bank debt
Interest coverage ratio		4.5
Short-term borrowing activities (excluding letters of credit)
Interest coverage ratio		4.5
AWR
Bank debt
Line of credit facility, current borrowing capacity				$ 200,000
AWR | Maximum
Bank debt
Line of credit facility, current borrowing capacity				$ 280,000
AWR | Long-term Debt
Bank debt
Balance Outstanding at December 31,		$ 255,500	$ 174,500
Short-term borrowing activities (excluding letters of credit)
Balance Outstanding at December 31,		$ 255,500	$ 174,500
AWR | Short-term borrowing (excluding letters of credit)
Bank debt
Interest Rate at the end of the period (as a percent)		5.07%	0.78%
Average Amount Outstanding		$ 213,758	$ 139,926
Weighted Average Annual Interest Rate (as a percent)		2.56%	0.91%
Maximum Amount Outstanding		$ 255,500	$ 174,500
Short-term borrowing activities (excluding letters of credit)
Interest Rate at the end of the period (as a percent)		5.07%	0.78%
Average Amount Outstanding		$ 213,758	$ 139,926
Weighted Average Annual Interest Rate (as a percent)		2.56%	0.91%
Maximum Amount Outstanding		$ 255,500	$ 174,500
AWR | Syndicated revolving credit facility
Bank debt
Interest coverage ratio		6.32
Total funded debt ratio		0.51
Short-term borrowing activities (excluding letters of credit)
Interest coverage ratio		6.32
Total funded debt ratio		0.51
AWR | Syndicated revolving credit facility | BVESI
Bank debt
Total funded debt ratio		0.65
Short-term borrowing activities (excluding letters of credit)
Total funded debt ratio		0.65
AWR | Syndicated revolving credit facility | Maximum
Bank debt
Total funded debt ratio		1.00
Short-term borrowing activities (excluding letters of credit)
Total funded debt ratio		1.00
AWR | Syndicated revolving credit facility | Minimum
Bank debt
Interest coverage ratio		3.25
Total funded debt ratio		0.65
Short-term borrowing activities (excluding letters of credit)
Interest coverage ratio		3.25
Total funded debt ratio		0.65
AWR | Syndicated revolving credit facility | Letters of credit
Bank debt
Maximum borrowing capacity		$ 25,000
Letter of credit, amount		$ 639
Letter of credit fee (as a percent)		0.65%
4.548% note due 2032
Bank debt
Interest rate per annum (as a percent)		4.548%
Short-term borrowing activities (excluding letters of credit)
Interest rate per annum (as a percent)		4.548%
4.548% note due 2032 | BVESI
Bank debt
Debt Instrument, Face Amount		$ 17,500
Short-term borrowing activities (excluding letters of credit)
Debt Instrument, Face Amount		$ 17,500
4.949% note due 2037
Bank debt
Interest rate per annum (as a percent)		4.949%
Short-term borrowing activities (excluding letters of credit)
Interest rate per annum (as a percent)		4.949%
4.949% note due 2037 | BVESI
Bank debt
Debt Instrument, Face Amount		$ 17,500
Short-term borrowing activities (excluding letters of credit)
Debt Instrument, Face Amount		$ 17,500