Fair value measurements Quantitative Information About Level 3 Fair Value Measurements (Details) - Level 3 - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Mortgage servicing rights \| Discounted cash flow
Fair value measurements
Fair value		$ 1,240
Weighted average prepayment speed		12.20%
Mortgage servicing rights \| Discounted cash flow \| Minimum
Fair value measurements
Prepayment speed		6.70%
Mortgage servicing rights \| Discounted cash flow \| Maximum
Fair value measurements
Prepayment speed		22.40%
Discount rate		9.60%
Weighted average discount rate		9.60%
Residential loan \| Fair value of property or collateral
Fair value measurements
Fair value	$ 50	$ 2,297
Fair Value Assumptions, Selling Cost, Percent	7.00%	7.00%
Appraised value, weighted average rate (as a percent)		83.00%
Residential loan \| Fair value of property or collateral \| Minimum
Fair value measurements
Appraised value (as a percent)		39.00%
Residential loan \| Fair value of property or collateral \| Maximum
Fair value measurements
Appraised value (as a percent)		99.00%
Home equity line of credit \| Fair value of property or collateral
Fair value measurements
Fair value	$ 128	$ 3
Fair Value Assumptions, Selling Cost, Percent	7.00%	7.00%
Commercial loans \| Fair value of property or collateral
Fair value measurements
Fair value		$ 145
Loans
Fair value measurements
Fair value	$ 178	2,445
Real estate acquired in settlement of loans \| Fair value of property or collateral
Fair value measurements
Fair value	$ 1,030	$ 288
Fair Value Assumptions, Selling Cost, Percent	7.00%	7.00%
Appraised value (as a percent)	100.00%	100.00%
Appraised value, weighted average rate (as a percent)	100.00%	100.00%

Fair Value Assumptions, Appraised Value, Weighted Average Rate

No definition available.

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

- Definition

Fair Value Assumptions, Selling Cost, Percent

+ References

No definition available.

+ Details

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

- Definition

Represents the appraised value used as an input to measure fair value, expressed as a percentage.

+ References

No definition available.

+ Details

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

- Definition

Fair Value Inputs, Discount Rate, Weighted Average

+ References

No definition available.

+ Details

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

- Definition

Fair Value Inputs, Prepayment Rate, Weighted Average

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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

- Definition

Rate at which loans or a loan portfolio are expected to prepay principal balances, used as an input to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

+ Details

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

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ServicingContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=he_DiscountedCashFlowMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_ValuationTechniqueAxis=he_FairValueOfPropertyOrCollateralMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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