Electric utility segment - Army Privatization (Details) - Hawaiian Electric Company, Inc. and Subsidiaries $ in Millions	Mar. 01, 2022 USD ($)	Oct. 30, 2020 USD ($) installation
Regulatory Projects and Legal Obligations [Line Items]
Public utilities, electric distribution system, contract period (in years)	50 years	50 years
Number of U.S. army installations being serviced \| installation		12
Purchase price	$ 14.5
price of acquisition, expected		$ 4.0
Transition period (in years)	1 year
Capital upgrade over the period (in years)	6 years

Number Of U.S. Army Installations Being Serviced

No definition available.

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Public Utilities, Electric Distribution System, Acquisition Purchase Price

No definition available.

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Public Utilities, Electric Distribution System, Capital Upgrade Period

No definition available.

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Public Utilities, Electric Distribution System, Contract Period

No definition available.

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Public Utilities, Electric Distribution System, Price Of Acquiring Additional Assets, Expected

No definition available.

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Public Utilities, Electric Distribution System, Transition Period

No definition available.

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-- None. No documentation exists for this element. --

No definition available.

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