Earnings Per Share / Capital Stock -Schedule of EPS (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Basic
Net Income		$ 119,268	$ 124,921	$ 78,396
Less: impact from participating securities		419	372	197
Total income available to common shareholders		$ 118,849	$ 124,549	$ 78,199
Weighted average Common Shares outstanding, basic		37,464,000	36,976,000	36,955,000
Basic earnings per Common Share (usd per share)		$ 3.17	$ 3.37	$ 2.12
Diluted
Total income available to common shareholders		$ 118,849	$ 124,549	$ 78,199
Undistributed earnings for dilutive stock-based awards		183	189	55
Total common shareholders earnings, diluted		$ 119,032	$ 124,738	$ 78,254
Weighted average Common Shares outstanding, basic		37,464,000	36,976,000	36,955,000
Stock-based compensation (in shares)	[1]	119,000	101,000	84,000
Weighted Average Number of Diluted Shares (in shares)		37,583,000	37,077,000	37,039,000
Earnings Per Share, Diluted		$ 3.17	$ 3.36	$ 2.11
Capital stock
Weighted Average Number of Shares Outstanding (in shares)		37,464,000	36,976,000	36,955,000
Sale of Stock, Consideration Received on Transaction		$ 89,500
AWR
Basic
Net Income		$ 119,268	$ 124,921	$ 78,396
Weighted average Common Shares outstanding, basic		37,464,000	36,976,000	36,955,000
Basic earnings per Common Share (usd per share)		$ 3.17	$ 3.37	$ 2.12
Diluted
Weighted average Common Shares outstanding, basic		37,464,000	36,976,000	36,955,000
Weighted Average Number of Diluted Shares (in shares)		37,583,000	37,077,000	37,039,000
Earnings Per Share, Diluted		$ 3.17	$ 3.36	$ 2.11
Capital stock
Weighted Average Number of Shares Outstanding (in shares)		37,464,000	36,976,000	36,955,000
Restricted Stock Units
Diluted
Restricted stock units outstanding (in shares)		144,799	115,684	96,988
Capital stock
Restricted stock units outstanding (in shares)		144,799	115,684	96,988

[1] (1)         In applying the treasury stock method of reflecting the dilutive effect of outstanding stock-based compensation in the calculation of diluted EPS, 144,799, 115,684 and 96,988 restricted stock units, including performance awards to officers of AWR, at December 31, 2024, 2023 and 2022, respectively, were deemed to be outstanding in accordance with accounting guidance on earnings per share.