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v3.21.1

Electric utility segment - Unconsolidated variable interest entities (Details) | 3 Months Ended
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Mar. 31, 2021 entity agreement MW
Power purchase agreement |
Number of IPPs (in entities) | entity | 3
Puna Geothermal Venture Power Purchase Agreement |
Power purchase agreement |
Firm capacity volume (in megawatts) | MW | 13
Hawaiian Electric Company |
Power purchase agreement |
Number of power purchase agreements (PPAs) (in agreements) | agreement | 5

X
- Definition Represents the number of firm power purchase agreements entered into, by the company. + References No definition available. + Details
Name: | he_NumberOfPowerPurchaseAgreements
Namespace Prefix: | he_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition -- None. No documentation exists for this element. -- + References No definition available. + Details
Name: | he_PowerPurchaseAgreementAbstract
Namespace Prefix: | he_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Power Purchase Agreement, Firm Capacity Volume + References No definition available. + Details
Name: | he_PowerPurchaseAgreementFirmCapacityVolume
Namespace Prefix: | he_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Variable Interest Entity Number Of Consolidated VIEs + References No definition available. + Details
Name: | he_VariableInterestEntityNumberOfConsolidatedVIEs
Namespace Prefix: | he_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_LongTermContractForPurchaseOfElectricPowerAxis=he_PunaGeothermalVenturePowerPurchaseAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=srt_SubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |