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

The assumed health care cost trend rate that will be graded down to and used for the 8th fiscal year and thereafter 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_DefinedBenefitPlanHealthCareCostTrendRateAssumedForGradingDownPlanInEightFiscalYearsThereafter
Namespace Prefix:	he_
Data Type:	num: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:	num: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:	num:percentItemType
Balance Type:	na
Period Type:	duration

Defined Benefit Plan, Health Care Trend Rates, Age Threshold

No definition available.

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

Defined Benefit Plan Increase in Senior Health Care Cost Trend Rate

No definition available.

Name:	he_DefinedBenefitPlanIncreaseinSeniorHealthCareCostTrendRate
Namespace Prefix:	he_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Defined Benefit Plan Increase in Senior Health Care Cost Trend Rate, Next 12 Months

No definition available.

Name:	he_DefinedBenefitPlanIncreaseinSeniorHealthCareCostTrendRateNext12Months
Namespace Prefix:	he_
Data Type:	num: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:	num: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:	num: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:	num: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:	num: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:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the contributions made by the employer in defined contribution plan.

No definition available.

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

Percentage employer matches of the employee's percentage contribution matched.

No definition available.

Name:	he_DefinedContributionPlanEmployerMatchingContributionPercentofMatch
Namespace Prefix:	he_
Data Type:	num: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

Represents the recovery period of prepaid pension assets, which are included in regulatory assets.

No definition available.

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

The interest rate used to adjust for the time value of money for the plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (m)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (m)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (m)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (m)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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

Amount of benefits from a defined benefit plan expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.