Revenues - Narrative (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025 USD ($) contract	Jun. 30, 2025 USD ($) contract
ASUS
Disaggregation of Revenue [Line Items]
Revenue recognized	$ 2.8	$ 3.9
Revenue, remaining performance obligation, amount	$ 4,200.0	$ 4,200.0
ASUS \| Minimum
Disaggregation of Revenue [Line Items]
Period of fixed price contracts to operate and maintain water systems at various military bases		14 years
ASUS \| Maximum
Disaggregation of Revenue [Line Items]
Period of fixed price contracts to operate and maintain water systems at various military bases		50 years
Revenue, remaining performance obligation, expected timing of satisfaction, period	49 years	49 years
Bay State Utility Service LLC (" BSUS")
Disaggregation of Revenue [Line Items]
Number of contracts with 15 year contract \| contract	1	1
Golden State Water Company and Bear Valley Electric Service Inc. \| Sales \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration risk, percentage		90.00%
Contracted services: \| Bay State Utility Service LLC (" BSUS")
Disaggregation of Revenue [Line Items]
Period of fixed price contracts to operate and maintain water systems at various military bases		15 years

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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