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v3.25.0.1

Rate and Regulatory Matters (Details) - USD ($) $ in Thousands |  |  |  |  | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 01, 2025 | Nov. 26, 2024 | May 26, 2024 | Mar. 01, 2024 | Feb. 28, 2025 | Oct. 30, 2024 | Aug. 31, 2024 | Oct. 31, 2023 | Dec. 31, 2024 | Sep. 30, 2024 | Jun. 30, 2024 | Mar. 31, 2024 | Dec. 31, 2023 | Sep. 30, 2023 | Jun. 30, 2023 | Mar. 31, 2023 | Dec. 31, 2024 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Nov. 30, 2021
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Approved increase in annual operating revenues |  | $ 600 | $ 500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Base rate amount |  |  |  |  |  |  |  | $ 5,500 |  |  |  |  |  |  |  |  |  | $ 563,100 |  |  |
Return on equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9.60% |  |  |
Reclassification regulatory liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 48,300 |  |
Depreciation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 24,430 | 25,194 | $ 23,029 |
Carrying costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,100 |  |  |
Previously incurred operating treatment costs |  |  |  |  |  |  |  |  | $ 2,600 |  |  |  |  |  |  |  | $ 2,600 | 2,600 |  |  |
Regulatory costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 600 |  |  |  |
Distribution system improvement charge rate |  |  |  |  |  |  |  | 5.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Annual operating revenue |  |  |  |  |  |  | $ 10,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of current revenue |  |  |  |  |  |  | 25.66% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Annual revenues |  |  |  |  |  |  |  |  | 47,107 | $ 55,100 | $ 49,146 | $ 40,524 | $ 38,602 | $ 46,715 | $ 42,801 | $ 38,156 |  | 191,877 | 166,274 |  |
Additional cost of purchased water |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,500 | 8,500 | 7,100 |
Operations and maintenance expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 92,363 | 83,113 | $ 79,096 |
Utility assets |  |  |  |  |  |  |  |  | $ 156,829 |  |  |  | $ 129,174 |  |  |  | $ 156,829 | $ 156,829 | $ 129,174 |  |
Price index rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3.00% |  |  |
New Jersey Board of Public Utilities [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Depreciation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 900 |  |  |
Lead Service Line Replacement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Previously incurred operating treatment costs |  |  |  |  |  |  |  |  |  |  | $ 1,200 |  |  |  |  |  |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate tax rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 35.00% |  |  |
Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate tax rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 21.00% |  |  |
Middlesex Water [Member] | New Jersey Board of Public Utilities [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Approved increase in annual operating revenues |  |  |  | $ 15,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maturity Less than 30 Days [Member] | Middlesex Water Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Escrow account |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,700
Tidewater [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Annual revenues |  |  |  |  |  | $ 2,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Additional cost of purchased water |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,100 |  |  |
Operations and maintenance expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,800 |  |  |
Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Rate and Regulatory Matters [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Approved increase in annual operating revenues | $ 100 |  |  |  | $ 500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Utility assets |  |  |  |  | $ 4,600 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in annual operating revenues | 6.51% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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