Share-based compensation - Related Income Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 10.4	$ 9.1	$ 5.8
Income tax benefit	2.1	1.4	1.0
Hawaiian Electric Company, Inc. and Subsidiaries
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	3.0	2.7	1.8
Income tax benefit	$ 0.7	$ 0.6	$ 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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- 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

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