Debt Instrument, Collateral, Size Of Facility

No definition available.

Name:	he_DebtInstrumentCollateralSizeOfFacility
Namespace Prefix:	he_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Covenant, Service Coverage Ratio, Minimum

+ References

No definition available.

+ Details

Name:	he_DebtInstrumentCovenantServiceCoverageRatioMinimum
Namespace Prefix:	he_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Covenant, Threshold Debt Proceeds Applied As Repayment Of Term Loan

+ References

No definition available.

+ Details

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

- Definition

Debt Instrument, Redemption, Amount

+ References

No definition available.

+ Details

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

- Definition

Debt Instrument, Written Notice To Purchaser Requirement, Period Prior To Funding

+ References

No definition available.

+ Details

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

- Definition

Line Of Credit Facility, Additional Borrowing Capacity

+ References

No definition available.

+ Details

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

- Definition

Represents the number of financial institutions with which the entity entered into a revolving Non Collateralized credit agreement with a letter of credit sub-facility.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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

- 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

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

- Definition

Amount of the required periodic payments including both interest and principal payments.

+ References

+ Details

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

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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

- Definition

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.

+ References

+ Details

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

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ References

+ Details

Name:	us-gaap_LongTermDebtPercentageBearingFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=he_A364DayRevolverMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=he_A364DayTermLoanCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Credit agreements and changes in debt - Narrative (Details)	Oct. 29, 2020	Sep. 28, 2020 USD ($) MW	May 19, 2020 USD ($)	Apr. 20, 2020 USD ($) institution	Sep. 30, 2020 USD ($) institution	Sep. 11, 2020 USD ($)	Dec. 31, 2019 USD ($)
Credit agreement
Number of financial institutions \| institution					8
Line of credit outstanding					$ 0		$ 0
Hawaiian Electric (parent only)
Credit agreement
Extinguishment of debt			$ 100,000,000
Hawaiian Electric (parent only) \| 364-Day Revolver \| Revolving Credit Facility
Credit agreement
Number of financial institutions \| institution				4
Credit agreement				$ 75,000,000
Line of credit outstanding					0
Line of credit facility \| HEI Facility
Credit agreement
Credit agreement					150,000,000
Increase in borrowing capacity				65,000,000
Threshold debt proceeds applied as repayment of term loan				$ 50,000,000
Line of credit facility \| Hawaiian Electric (parent only) \| Hawaiian Electric Facility
Credit agreement
Credit agreement					$ 200,000,000
Term Loan
Credit agreement
Number of financial institutions \| institution				2
Credit agreement				$ 65,000,000
Term Loan \| Hawaiian Electric (parent only) \| 364-Day Term Loan Credit Agreement
Credit agreement
Credit agreement			50,000,000
Threshold debt proceeds applied as repayment of term loan			75,000,000
Draw down of debt			$ 50,000,000
Term Loan \| KWCL \| Non-recourse Term Loan Agreement
Credit agreement
Aggregate principal amount		$ 13,000,000
Solar facility (in MW) \| MW		6
Minimum debt service coverage ratio		1.10
Periodic principal and interest payments		$ 400,000
Term Loan \| KWCL \| Non-recourse Term Loan Agreement \| London Interbank Offered Rate (LIBOR)
Credit agreement
Basis spread on variable rate		2.00%
Senior Notes \| HEI Notes
Credit agreement
Aggregate principal amount						$ 50,000,000
Fixed interest rate						2.98%
Senior Notes \| HEI Notes \| On or Prior to December 29, 2020
Credit agreement
Redemption amount						$ 50,000,000
Senior Notes \| The Notes \| Subsequent Event
Credit agreement
Written notice to purchaser requirement, period prior to funding	7 days