Name:	he_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeRegulatoryAssetChargesBeforeTax
Namespace Prefix:	he_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Defined Benefit Plan, Actual Return On Assets, Percent

No definition available.

Name:	he_DefinedBenefitPlanActualReturnOnAssetsPercent
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Assumed Discount Rate, Active Manager Premium

No definition available.

Name:	he_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostAssumedDiscountRateActiveManagerPremium
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

An assumption for the next fiscal year as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

No definition available.

Name:	he_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedRateOfReturnOnAssetsForNextFiscalYear
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

-- None. No documentation exists for this element. --

No definition available.

Name:	he_DefinedBenefitPlanEstimatedFutureBenefitFundingAbstract
Namespace Prefix:	he_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the dental plan under the defined benefit plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

No definition available.

Name:	he_DefinedBenefitPlanHealthCareCostTrendRateAssumedForDentalPlanInNextFiscalYear
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Defined Benefit Plan, Health Care Cost Trend Rate Assumed For Grading Down Plan In Nine Fiscal Years Thereafter

No definition available.

Name:	he_DefinedBenefitPlanHealthCareCostTrendRateAssumedForGradingDownPlanInNineFiscalYearsThereafter
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the medical plan under the defined benefit plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

No definition available.

Name:	he_DefinedBenefitPlanHealthCareCostTrendRateAssumedForMedicalPlanInNextFiscalYear
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the vision plan under the defined benefit plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

No definition available.

Name:	he_DefinedBenefitPlanHealthCareCostTrendRateAssumedForVisionPlanInNextFiscalYear
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Grading Down Plan in Twelve Fiscal Years Thereafter

No definition available.

Name:	he_DefinedBenefitPlanHealthCareCostTrendRateAssumedforGradingDownPlaninTwelveFiscalYearsThereafter
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Represents the number of past years for adding or subtracting the unamortized differences from the fair value.

No definition available.

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

Represents the number of years for which regulatory asset/liability for each utilities will be amortized, beginning with the respective utility's next rate case.

No definition available.

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

Represents the percentage of valuation difference of plan assets amortized in the first year to determine market related value.

No definition available.

Name:	he_DefinedBenefitPlanPlanAssetsAtFairValuePercentageOfValuationDifferenceAmortizedInYearOne
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of valuation difference of plan assets amortized in two to five years to determine market related value.

No definition available.

Name:	he_DefinedBenefitPlanPlanAssetsAtFairValuePercentageOfValuationDifferenceAmortizedInYearsTwoToFive
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of the range around the fair value in valuation method.

No definition available.

Name:	he_DefinedBenefitPlanPlanAssetsAtFairValueRangeAroundFairValuePercentage
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Represents the threshold percentage to measure amounts to be recognized.

No definition available.

Name:	he_DefinedBenefitPlanPlanAssetsAtFairValueThresholdPercentageAroundFairValue
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Represents the vested percentage of interest of each affected participant if a participating employer terminates its participation in the plans up to the extent funded.

No definition available.

Name:	he_DefinedBenefitPlanVestedPercentageOfInterestOfEachAffectedParticipantAfterParticipatingEmployerTerminatesParticipation
Namespace Prefix:	he_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Represents the amount of executive life and nonqualified pension plan expenses, which are not recoverable.

No definition available.

Name:	he_ExecutiveLifeAndDefinedBenefitPlanNonqualifiedPensionPlanExpenses
Namespace Prefix:	he_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of pension benefit costs recognized during the period for defined benefit plans. Pension expense includes the following components: service cost, interest cost, expected return on plan assets, gain (loss) on plan assets, prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments, less the impact of Public Utilities Commission decisions and orders and capitalized amounts.

No definition available.

Name:	he_PensionExpenseLessPublicUtilitiesCommissionImpactAndCapitalizedAmounts
Namespace Prefix:	he_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

Amount of benefit for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following current fiscal year.

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

Amount of benefit for defined benefit plan expected to be paid in next fiscal year following current fiscal year.

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

Amount of benefit for defined benefit plan expected to be paid in fifth fiscal year following current fiscal year.

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

Amount of benefit for defined benefit plan expected to be paid in fourth fiscal year following current fiscal year.

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

Amount of benefit for defined benefit plan expected to be paid in third fiscal year following current fiscal year.

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

Amount of benefit for defined benefit plan expected to be paid in second fiscal year following current fiscal year.

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

Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (g)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 18
-URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921

Name:	us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of cost for defined contribution plan.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of discretionary contributions made by an employer to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

No definition available.

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

Amount of cost (reversal of cost) for other postretirement benefits. Excludes pension benefits.

No definition available.

Name:	us-gaap_OtherPostretirementBenefitExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
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