Earnings per Share/Capital Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
Feb. 27, 2024	Mar. 31, 2026	Mar. 31, 2025
Capital stock
Sale of stock, maximum consideration on transaction	$ 200,000
Agreement term (in years)	3 years
Sale of stock, number of shares issued in transaction (in shares)		84,237	334,548
Sale of stock, consideration received on transaction		$ 6,300	$ 25,800
Payments for commissions		100	400
Sale of Stock, remaining available for sale		34,300
Payments of stock issuance costs		$ 100	$ 100
Issuances of Common Shares under stock-based compensation plans (in shares)		25,946	23,014
Payment, tax withholding, share-based payment arrangement		$ 1,371	$ 1,301
Dividends paid		$ 19,699	$ 17,762
Dividends declared per common share (in dollars per share)		$ 0.5040	$ 0.4655
AWR
Capital stock
Dividends paid		$ 19,700	$ 17,800
GSWC
Capital stock
Payment, tax withholding, share-based payment arrangement		1,227	1,174
Dividends paid		$ 19,700	$ 0
Restricted Stock
Capital stock
Restricted stock units outstanding (in shares)		155,400	153,583

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Sale of Stock, Maximum Consideration On Transaction

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Sale of Stock, remaining available for sale under the ATM equity program

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Aggregate dividends paid during the period for each share of common stock outstanding.

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The amount of cash paid for commissions during the current period.

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Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

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The cash outflow for cost incurred directly with the issuance of an equity security.

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Amount of cash outflow to satisfy grantee's tax withholding obligation for award under share-based payment arrangement.

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Cash received on stock transaction after deduction of issuance costs.

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The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP).

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