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Electric utility segment - Power purchase agreements (Details) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jul. 31, 2018 MW | Jun. 30, 2015 MW | May 31, 2012 MW | Mar. 31, 1988 MW | Mar. 31, 2021 USD ($) | Mar. 31, 2020 USD ($) | Dec. 31, 1988 MW
Hu Honua Bioenergy, LLC |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Minimum power volume required (in megawatts) | MW |  |  | 21.5 |  |  |  |
Molokai New Energy Partners |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Total contracted PV capacity (in megawatts) | MW | 4.88 |  |  |  |  |  |
Total contracted battery energy storage system capacity | MW | 3 |  |  |  |  |  |
Maximum power volume to be delivered (in megawatts) | MW | 2.64 |  |  |  |  |  |
AES Hawaii |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchase commitment, period (in years) |  |  |  | 30 years |  |  |
Minimum power volume required (in megawatts) | MW |  |  |  | 180 |  |  |
Additional capacity requirement (in megawatts) | MW |  | 9 |  |  |  |  |
Hawaiian Electric (parent only) |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | $ 142 | $ 140 |
Hawaiian Electric (parent only) | Kalaeloa |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | 37 | 38 |
Increased power purchase commitment capacity (in megawatts) | MW |  |  |  |  |  |  | 208
Hawaiian Electric (parent only) | AES Hawaii |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | 30 | 31 |
Hawaiian Electric (parent only) | HPOWER |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | 17 | 17 |
Hawaiian Electric (parent only) | Hamakua Energy |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | 11 | 13 |
Hawaiian Electric (parent only) | Puna Geothermal Venture |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | 4 | 0 |
Hawaiian Electric (parent only) | Wind IPPs |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | 29 | 28 |
Hawaiian Electric (parent only) | Solar IPPs |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | 12 | 11 |
Hawaiian Electric (parent only) | Other IPPs |  |  |  |  |  |  |
Regulatory Projects and Legal Obligations [Line Items] |  |  |  |  |  |  |
Purchased power |  |  |  |  | $ 2 | $ 2 |

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- Definition Aggregate of Power Purchase Capacity Increases from Initial Capacity + References No definition available. + Details
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- Definition Long-term Contract For Purchase Of Electric Power, Maximum Power Volume Delivered + References No definition available. + Details
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- Definition Long-term Contract For Purchase Of Electric Power, Total Contracted Battery Energy Storage System Capacity + References No definition available. + Details
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- Definition Long-term Contract For Purchase Of Electric Power, Total Contracted PV Capacity + References No definition available. + Details
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- Definition Long Term Purchase Commitment, Arbitration, Additional Capacity Requirement + References No definition available. + Details
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- Definition Period covered by the long-term purchase commitment, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition Amount of operating expense for purchased power of regulated operation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
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