Name:	he_DebtInstrumentCovenantConsolidatedDebtToTotalConsolidatedCapitalizationRatio
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Represents the consolidated subsidiary debt to total consolidated capitalization ratio which the entity is required to maintain pursuant to a debt covenant.

No definition available.

Name:	he_DebtInstrumentCovenantConsolidatedSubsidiaryDebtToTotalConsolidatedCapitalizationRatio
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Represents the nonconsolidated capitalization ratio, which the entity is required to maintain pursuant to a debt covenant.

No definition available.

Name:	he_DebtInstrumentCovenantNonconsolidatedCapitalizationRatio
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Debt Instrument, Number Of Instruments Entered Into During Period

No definition available.

Name:	he_DebtInstrumentNumberOfInstrumentsEnteredIntoDuringPeriod
Namespace Prefix:	he_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Line of Credit Facility, Accordion Feature, Increase Limit

No definition available.

Name:	he_LineOfCreditFacilityAccordionFeatureIncreaseLimit
Namespace Prefix:	he_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Line Of Credit Facility, Automatic Extension Expiration Period

No definition available.

Name:	he_LineOfCreditFacilityAutomaticExtensionExpirationPeriod
Namespace Prefix:	he_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Line Of Credit Facility, Extension Period

No definition available.

Name:	he_LineOfCreditFacilityExtensionPeriod
Namespace Prefix:	he_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Line Of Credit Facility, Number Of Extension Options

No definition available.

Name:	he_LineOfCreditFacilityNumberOfExtensionOptions
Namespace Prefix:	he_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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-SubTopic 605
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Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

No definition available.

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

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

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of borrowings classified as other, maturing within one year or the normal operating cycle, if longer.

Name:	us-gaap_OtherShortTermBorrowings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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-SubTopic 10
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Name:	us-gaap_ShortTermBorrowings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

No definition available.

Name:	us-gaap_ShortTermDebtLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_DebtInstrumentAxis=he_HEIFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_DebtInstrumentAxis=he_HawaiianElectricFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=he_HawaiianElectricCompanyAndSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=he_CreditFacilitiesEffectiveJuly2017Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CreditFacilityAxis=us-gaap_BridgeLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DebtInstrumentAxis=he_ABLCreditFacilityAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: