Share-based compensation - Summary of income taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based compensation
Share-based compensation expense	$ 1.7	$ 1.3	$ 7.3	$ 6.7
Income tax benefit	0.4	0.1	1.5	1.0
Hawaiian Electric Company, Inc. and Subsidiaries
Share-based compensation
Share-based compensation expense	0.6	0.1	2.1	2.1
Income tax benefit	$ 0.1	$ 0.0	$ 0.5	$ 0.4

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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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.

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