Credit agreement and changes in debt - Note purchase agreements (Details) - Senior Notes - Series 2022A	May 11, 2022 USD ($)
Debt Instrument [Line Items]
Aggregate principal amount	$ 60,000,000
Fixed coupon interest rate	3.70%
Hawaiian Electric
Debt Instrument [Line Items]
Aggregate principal amount	$ 40,000,000
Hawaii Electric Light
Debt Instrument [Line Items]
Aggregate principal amount	10,000,000
Maui Electric
Debt Instrument [Line Items]
Aggregate principal amount	$ 10,000,000

Face (par) amount of debt instrument at time of issuance.

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