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Electric utility segment - Rate proceedings (Details) - USD ($) $ in Millions | Nov. 13, 2019 | Aug. 21, 2019
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Hawaiian Electric (parent only) |  |
Regulatory Projects and Legal Obligations [Line Items] |  |
General rate increase, revenue |  | $ 77.6
Stipulated ROACE rate |  | 10.50%
General rate increase, revenue, percent |  | 4.10%
Assumptions on rate of return, return on average common equity, percentage decrease |  | 8.00%
HELCO |  |
Regulatory Projects and Legal Obligations [Line Items] |  |
Effective interest rate of return | 7.52% |
Stipulated ROACE rate | 9.50% |
Common equity capitalization rate | 58.00% |
Rate Base | $ 543.0 |
Interim revenue requirement | $ 387.0 |

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