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Summary of Significant Accounting Policies - Property, Plant and Equipment and Intangible Assets (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023
Major components of depreciable plant and equipment [Abstract] |  |  |
Source of supply | $ 243,335 | $ 228,621 |
Pumping plant | 331,134 | 301,280 |
Water treatment plant | 396,061 | 367,836 |
Transmission and distribution plant | 3,323,482 | 3,015,978 |
General plant | 394,632 | 335,599 |
Total depreciable plant and equipment | $ 4,688,644 | $ 4,249,314 |
Useful Lives |  |  |
Depreciation expense as percentage of beginning of year balance of depreciable plant | 2.75% | 2.90% | 2.90%
Capitalized interest costs | $ 7,335 | $ 3,524 | $ 2,900
Equity funds capitalized | 6,237 | 2,362 | 2,114
Water Plant |  |  |
Useful Lives |  |  |
Depreciation | $ 114,265 | $ 111,575 | $ 104,325
Minimum |  |  |
Useful Lives |  |  |
Source of supply | 20 years |  |
Pumping plant | 5 years |  |
Water treatment plant | 5 years |  |
Transmission and distribution plant | 10 years |  |
General plant | 5 years |  |
Useful life of intangible assets | 3 years |  |
Maximum |  |  |
Useful Lives |  |  |
Source of supply | 100 years |  |
Pumping plant | 70 years |  |
Water treatment plant | 62 years |  |
Transmission and distribution plant | 100 years |  |
General plant | 68 years |  |
Useful life of intangible assets | 70 years |  |

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