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Electric utility segment - Regulatory Proceedings (Details) $ in Thousands |  |  | 3 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Dec. 29, 2023 USD ($) | Dec. 23, 2020 USD ($) | Mar. 31, 2025 USD ($) project | Mar. 24, 2025 USD ($) | Dec. 31, 2024 USD ($) | Jun. 10, 2019 USD ($) | Oct. 31, 2018 USD ($)
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
PUC proposal period (in days) |  | 45 days |  |  |  |  |
Public utilities, modified pilot process proposal period (in days) |  |  | 15 days |  |  |  |
Propose pilots annual cap |  |  | $ 10,000 |  |  |  |
Regulatory assets |  |  | $ 233,050 |  | $ 227,424 |  |
Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Multi-year rate period (in years) |  | 5 years |  |  |  |  |
Customer dividend, negative adjustment percentage |  | 0.22% |  |  |  |  |
Savings commitment liability, annual rate |  | $ 6,600 |  |  |  |  |
Earnings sharing mechanism, actual return on equity, dead band percentage above or below target |  |  | 3.00% |  |  |  |
Approved return on equity, percentage |  |  | 9.50% |  |  |  |
Percentage sharing between customers and utilities |  |  | 0.50 |  |  |  |
Earnings sharing mechanism, actual earning, above or below dead band |  |  | 1.50% |  |  |  |
Percentage sharing for any further difference |  |  | 0.90 |  |  |  |
MPIR and EPRM requested amount |  |  | $ 35,700 |  |  |  |
EPRM approved projects | project |  |  | 4 |  |  |  |
EPRM approved projects, capital costs |  |  | $ 218,500 |  |  |  |
Number of projects | project |  |  | 2 |  |  |  |
Prior year deferred cost recovery approved |  |  |  | $ 2,100 |  |  |
Accrued earned rewards, net of penalties |  |  |  |  | $ 6,200 |  |
Recovery of deferral costs period (in years) | 3 years |  |  |  |  |  |
Hawaiian Electric Company, Inc. and Subsidiaries | Honolulu Generating Units 8 and 9 |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Regulatory asset amortization period |  |  | 9 years |  |  |  |
Regulatory assets |  |  | $ 25,900 |  |  |  |
Hawaiian Electric Company, Inc. and Subsidiaries | Waiau Generating Units 3 and 4 |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Regulatory asset amortization period |  |  |  |  | 9 years |  |
Regulatory assets |  |  | 13,900 |  |  |  |
Hawaiian Electric Company, Inc. and Subsidiaries | Suspension Of Disconnections |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Regulatory assets |  |  | 3,800 |  |  |  |
Hawaiian Electric Company, Inc. and Subsidiaries | Natural Disasters and Other Casualty Events |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Regulatory assets |  |  | 58,300 |  |  |  |
Hawaiian Electric Company, Inc. and Subsidiaries | COVID-19 |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Regulatory assets |  |  | 5,900 |  |  |  |
Public utilities in regulatory assets | $ 8,700 |  |  |  |  |  |
Hawaiian Electric, Parent |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Accrued earned rewards, net of penalties |  |  |  |  | $ 2,500 |  |
Hawaii Electric Light Company, Inc |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Accrued earned rewards, net of penalties |  |  |  |  | 3,400 |  |
Maui Electric |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Accrued earned rewards, net of penalties |  |  |  |  | $ 300 |  |
Schofield Generation Station | Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
MPIR requested amount |  |  | 15,600 |  |  |  |
West Loch PV Project | Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
MPIR requested amount |  |  | 3,100 |  |  |  |
Grid Modernization Strategy Phase 1 Project | Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
MPIR requested amount |  |  | 14,100 |  |  |  |
Waiawa UFLS Project | Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
EPRM requested amount |  |  | 100 |  |  |  |
Waena Switchyard/Synchronous Project | Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
EPRM requested amount |  |  | 2,500 |  |  |  |
Resilience Project | Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
EPRM requested amount |  |  | $ 300 |  |  |  |
ERP/EAM Implementation Project | Hawaiian Electric Company, Inc. and Subsidiaries |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
ERP/EAM project service period (in years) |  |  | 12 years |  |  |  |
ERP/EAM project service, savings over 12 years |  |  |  |  |  |  | $ 246,000
Future O&M expense reductions |  |  |  |  |  | $ 150,000 |
Future cost avoidance related to capital cost and tax costs |  |  |  |  |  | $ 96,000 |
Regulatory liability, amortization period (in years) |  |  | 5 years |  |  |  |
Regulatory liability for O&M expense reductions |  |  | $ 12,300 |  |  |  |
ERP/EAM Implementation Project | Hawaiian Electric, Parent |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Regulatory liability for O&M expense reductions |  |  | 800 |  |  |  |
ERP/EAM Implementation Project | Hawaii Electric Light Company, Inc |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Regulatory liability for O&M expense reductions |  |  | 4,600 |  |  |  |
ERP/EAM Implementation Project | Maui Electric |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Regulatory liability for O&M expense reductions |  |  | $ 6,900 |  |  |  |

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