XML 51 R35.htm IDEA: XBRL DOCUMENT v3.21.1

Electric utility segment - Utility projects (Details) - USD ($) $ in Millions		1 Months Ended		3 Months Ended
	Jun. 10, 2019	Nov. 30, 2020	Jan. 31, 2020	Mar. 31, 2021	Dec. 31, 2020
ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
ERP/EAM project service period (in years)	12 years
Future O&M expense reductions	$ 150.0
Future cost avoidance related to capital cost and tax costs	$ 96.0
Hawaiian Electric (parent only) | PCB Contamination
Public Utilities, General Disclosures [Line Items]
Valuation allowances and reserves				$ 9.8
Hawaiian Electric (parent only) | ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
ERP/EAM project service period (in years)		12 years
Regulatory liability for O&M expense reductions				6.5
HELCO | ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
ERP/EAM project service period (in years)			12 years
Regulatory liability for O&M expense reductions				1.9
Regulatory liability to be flowed through to customers					$ 1.6
Hawaiian Electric Company, Inc. and Subsidiaries | ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
Regulatory liability for O&M expense reductions				11.2
Maui Electric
Public Utilities, General Disclosures [Line Items]
Additional accrued investigation and estimated cleanup costs				2.7
Maui Electric | ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
Regulatory liability for O&M expense reductions				$ 2.8
Regulatory liability, amortization period				5 years
Regulatory liability to be flowed through to customers					$ 2.3

X

- Definition

Public Utility, ERP/EAM Project Service Period

+ References

No definition available.

+ Details

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

X

- Definition

Public Utility, ERP/EAM Regulatory Liability For Operation And Maintenance Expense Reductions

+ References

No definition available.

+ Details

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

X

- Definition

Public Utility, ERP/EAM Regulatory Liability To Be Flowed Through To Customers

+ References

No definition available.

+ Details

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

X

- Definition

Public Utility, ERP/EAM System, Future Cost Avoidance Related To Capital Cost And Tax Cost

+ References

No definition available.

+ Details

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

X

- Definition

Public Utility, ERP/EAM System, Future Operation And Maintenance Expense Reductions

+ References

No definition available.

+ Details

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

X

- Definition

Represents the amount of additional accrued investigation and estimated cleanup costs.

+ References

No definition available.

+ Details

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

X

- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

+ Details

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

X

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

X

- Definition

Amortization period for the recovery of regulatory liability, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_RegulatoryLiabilityAmortizationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis=he_ERPEAMImplementationProjectMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

Name:	us-gaap_EnvironmentalRemediationContingencyAxis=he_PCBContaminationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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

X

- Details

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

X

- Details

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