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Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | $ 29,184 | $ 54,679
GSWC |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | (13,874) | 18,173
GSWC | Deferred Income Tax Charge |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | (63,464) | (63,682)
GSWC | Pension Costs and Other Postretirement Benefit Costs |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | (24,578) | (25,179)
GSWC | PFAS Contamination Litigation Proceeds Memorandum Account |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | (12,393) | 0
GSWC | Other regulatory liabilities |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | (1,758) | (608)
BVES |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 43,058 | 36,506
BVES | Other regulatory liabilities |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | (4,489) | (5,628)
2025 general rate case memorandum accounts (unbilled revenue) | GSWC |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 2,614 | 0
2022/2023 general rate case memorandum accounts (unbilled revenue) | GSWC |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 25,864 | 37,711
Water revenue adjustment mechanism, net of modified cost balancing account | GSWC |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 12,752 | 29,738
Asset retirement obligations | GSWC |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 7,981 | 7,501
Flowed-through deferred income taxes, net | GSWC |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 18,668 | 12,506
Low income rate assistance balancing accounts | GSWC |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 10,063 | 8,834
Other regulatory assets | GSWC |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 10,377 | 11,352
Other regulatory assets | BVES |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 11,293 | 8,853
Derivative instrument memorandum account (Note 5) | BVES |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 14,275 | 8,823
2023/2024 General Rate Case Memorandum accounts ( unbilled revenue) | BVES |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | 8,949 | 9,777
Wildfire mitigation and other fire prevention related costs memorandum accounts | BVES |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Net regulatory Assets | $ 13,030 | $ 14,681

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- Definition The net amount of all regulatory assets less all regulatory liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478742/980-340-50-1 + Details
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