Fair value measurements Quantitative Information About Level 3 Fair Value Measurements (Details) - Level 3 - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Residential loan \| Fair value of property or collateral
Fair value measurements
Fair value	$ 2,297	$ 2,361
Appraised value, weighted average rate (as a percent)	83.00%	87.00%
Residential loan \| Fair value of property or collateral \| Minimum
Fair value measurements
Appraised value (as a percent)	39.00%	44.00%
Residential loan \| Fair value of property or collateral \| Maximum
Fair value measurements
Appraised value (as a percent)	99.00%	96.00%
Home equity line of credit \| Fair value of property or collateral
Fair value measurements
Fair value	$ 3	$ 170
Appraised value, weighted average rate (as a percent)	7.00%	50.00%
Home equity line of credit \| Fair value of property or collateral \| Minimum
Fair value measurements
Appraised value (as a percent)		45.00%
Home equity line of credit \| Fair value of property or collateral \| Maximum
Fair value measurements
Appraised value (as a percent)		50.00%
Commercial loan 1 \| Fair value of property or collateral
Fair value measurements
Fair value	$ 145	$ 217
Fair value of business assets (as a percent)	91.00%	19.00%
Tax credit investments
Fair value measurements
Fair value	$ 8,975
Tax credit investments \| Fair value of property or collateral \| Minimum
Fair value measurements
Appraised value (as a percent)	5.00%
Tax credit investments \| Fair value of property or collateral \| Maximum
Fair value measurements
Appraised value (as a percent)	93.00%
Tax credit investments \| Discounted cash flow
Fair value measurements
Fair value of business assets (as a percent)	88.00%
Weighted average discount rate	7.00%
Loans
Fair value measurements
Fair value	$ 2,445	$ 4,416
Real estate acquired in settlement of loans \| Fair value of property or collateral
Fair value measurements
Fair value	$ 288
Appraised value, weighted average rate (as a percent)	100.00%
Appraised value (as a percent)	100.00%
Commercial loan 2 \| Discounted cash flow
Fair value measurements
Fair value		$ 1,668
Present value of expected future cash flows (as a percent)		58.00%
Weighted average discount rate		4.50%

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

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

Represents the fair value of business assets used as an input to measure fair value, expressed as a percentage.

+ References

No definition available.

+ Details

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

- Definition

Represents the anticipated debt restructuring for pay down of loan used as an input to measure fair value, expressed as a percentage.

+ References

No definition available.

+ Details

Name:	he_FairValueInputsPaydownOfLoansRate
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

- Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=he_CommercialLoan1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=he_TaxCreditInvestmentsMember
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_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:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=he_CommercialLoan2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: