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Electric utility segment - Fuels Barging Contract (Details) - Sause Bros., Inc. $ in Millions | Aug. 23, 2021 USD ($)
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Long-term Purchase Commitment [Line Items] |
Purchase commitment, period | 5 years
Annual base rent amount | $ 6.2

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- Definition Long-Term Purchase Commitment, Annual Base Rent + References No definition available. + Details
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Namespace Prefix: | he_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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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
Name: | us-gaap_LongtermPurchaseCommitmentPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | srt_CounterpartyNameAxis=he_SauseBrosIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |