Income taxes (Details)	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024
Income Tax Contingency [Line Items]
Effective income tax, percent	25.00%	26.00%
Hawaiian Electric Company, Inc. and Subsidiaries
Income Tax Contingency [Line Items]
Effective income tax, percent	22.00%	26.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 231
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-231

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration