Bank segment - Credit risk profile - nonaccrual loans (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2022	Dec. 31, 2021
Credit risk profile based on nonaccrual loans
With a Related ACL	$ 14,089	$ 37,764
Without a Related ACL	6,043	7,210
Total	20,132	44,974
Total troubled debt restructuring loans not included above	28,986	24,917
Real estate \| Residential 1-4 family
Credit risk profile based on nonaccrual loans
With a Related ACL	6,125	16,045
Without a Related ACL	4,219	3,703
Total	10,344	19,748
Total troubled debt restructuring loans not included above	7,671	6,949
Real estate \| Commercial real estate
Credit risk profile based on nonaccrual loans
With a Related ACL	0	14,104
Without a Related ACL	0	1,221
Total	0	15,325
Total troubled debt restructuring loans not included above	9,633	3,055
Real estate \| Home equity line of credit
Credit risk profile based on nonaccrual loans
With a Related ACL	3,715	4,227
Without a Related ACL	916	1,294
Total	4,631	5,521
Total troubled debt restructuring loans not included above	4,814	6,021
Real estate \| Residential land
Credit risk profile based on nonaccrual loans
With a Related ACL	312	97
Without a Related ACL	97	300
Total	409	397
Total troubled debt restructuring loans not included above	806	980
Real estate \| Commercial construction
Credit risk profile based on nonaccrual loans
With a Related ACL	0	0
Without a Related ACL	0	0
Total	0	0
Total troubled debt restructuring loans not included above	0	0
Real estate \| Residential construction
Credit risk profile based on nonaccrual loans
With a Related ACL	0	0
Without a Related ACL	0	0
Total	0	0
Total troubled debt restructuring loans not included above	0	0
Commercial
Credit risk profile based on nonaccrual loans
With a Related ACL	2,591	1,446
Without a Related ACL	811	692
Total	3,402	2,138
Total troubled debt restructuring loans not included above	6,011	7,860
Consumer
Credit risk profile based on nonaccrual loans
With a Related ACL	1,346	1,845
Without a Related ACL	0	0
Total	1,346	1,845
Total troubled debt restructuring loans not included above	$ 51	$ 52

Financing Receivable, Nonaccrual, With Allowance

No definition available.

Name:	he_FinancingReceivableNonaccrualWithAllowance
Namespace Prefix:	he_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized cost of financing receivable on nonaccrual status with no allowance for credit loss. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447

+ Details

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

- Definition

Amortized cost of financing receivable on nonaccrual status. Excludes net investment in lease.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123577603&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919258-210447

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (3)

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph (a)
-Subparagraph (2)

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_FinancingReceivableRecordedInvestmentPastDueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=he_RealEstatePortfolioSegmentMember
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_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:

- 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: