Bank segment - Schedule of Loan Modification (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2024
Financing Receivable, Modified [Line Items]
Total	$ 2,143	$ 7,576
% of total class of loans	0.04%	0.13%
Term extension
Financing Receivable, Modified [Line Items]
Total	$ 50	$ 315
Payment delay
Financing Receivable, Modified [Line Items]
Total	2,093	6,053
Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	0	1,208
Commercial
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
% of total class of loans	0.00%	0.00%
Commercial \| Term extension
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
Commercial \| Payment delay
Financing Receivable, Modified [Line Items]
Total	0	0
Commercial \| Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	0	0
Consumer
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
% of total class of loans	0.00%	0.00%
Consumer \| Term extension
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
Consumer \| Payment delay
Financing Receivable, Modified [Line Items]
Total	0	0
Consumer \| Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	0	0
Residential 1-4 family \| Real estate
Financing Receivable, Modified [Line Items]
Total	$ 2,143	$ 5,246
% of total class of loans	0.08%	0.20%
Residential 1-4 family \| Real estate \| Term extension
Financing Receivable, Modified [Line Items]
Total	$ 50	$ 315
Residential 1-4 family \| Real estate \| Payment delay
Financing Receivable, Modified [Line Items]
Total	2,093	4,931
Residential 1-4 family \| Real estate \| Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	0	0
Commercial real estate \| Real estate
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 1,208
% of total class of loans	0.00%	0.09%
Commercial real estate \| Real estate \| Term extension
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
Commercial real estate \| Real estate \| Payment delay
Financing Receivable, Modified [Line Items]
Total	0	0
Commercial real estate \| Real estate \| Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	0	1,208
Home equity line of credit \| Real estate
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 447
% of total class of loans	0.00%	0.05%
Home equity line of credit \| Real estate \| Term extension
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
Home equity line of credit \| Real estate \| Payment delay
Financing Receivable, Modified [Line Items]
Total	0	447
Home equity line of credit \| Real estate \| Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	0	0
Residential land \| Real estate
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 675
% of total class of loans	0.00%	3.24%
Residential land \| Real estate \| Term extension
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
Residential land \| Real estate \| Payment delay
Financing Receivable, Modified [Line Items]
Total	0	675
Residential land \| Real estate \| Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	0	0
Commercial construction \| Real estate
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
% of total class of loans	0.00%	0.00%
Commercial construction \| Real estate \| Term extension
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
Commercial construction \| Real estate \| Payment delay
Financing Receivable, Modified [Line Items]
Total	0	0
Commercial construction \| Real estate \| Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	0	0
Residential construction \| Real estate
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
% of total class of loans	0.00%	0.00%
Residential construction \| Real estate \| Term extension
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0
Residential construction \| Real estate \| Payment delay
Financing Receivable, Modified [Line Items]
Total	0	0
Residential construction \| Real estate \| Combination payment delay & term extension
Financing Receivable, Modified [Line Items]
Total	$ 0	$ 0

Amortized cost excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

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

- Definition

Percentage, excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty to total financing receivables.

+ References

+ Details

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

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-34

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 33
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-33

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-42

+ Details

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

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=us-gaap_PaymentDeferralMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanRestructuringModificationAxis=he_CombinationPaymentDelayAndTermExtensionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=he_Residential14FamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=he_RealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=he_ResidentialLandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=he_CommercialConstructionLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=he_ResidentialConstructionLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: