Electric utility segment - Commitments and Contingencies (Details) $ in Millions			1 Months Ended			12 Months Ended
	Sep. 01, 2023 USD ($)	Sep. 15, 2020 agreement	Feb. 28, 2023	Jul. 31, 2018 MW	May 31, 2012 MW	Dec. 31, 2023 USD ($) agreement contract MW	Dec. 31, 2022 USD ($)
Regulatory Projects and Legal Obligations [Line Items]
Valuation allowances and reserves, statement of financial position, not disclosed						reserve account balance
Environmental remediation expense, statement of income or comprehensive income, extensible enumeration, not disclosed	remediation costs
Hu Honua Bioenergy
Regulatory Projects and Legal Obligations [Line Items]
Purchase commitment, minimum power volume required to be purchased					21.5
Molokai New Energy Partners
Regulatory Projects and Legal Obligations [Line Items]
Total contracted PV capacity (in megawatts)				4.88
Total contracted battery energy storage system capacity				3
Maximum power volume to be delivered (in megawatts)				2.64
Maui Electric
Regulatory Projects and Legal Obligations [Line Items]
Additional accrued investigation and estimated cleanup costs | $						$ 2.6
Hawaiian Electric | PCB Contamination
Regulatory Projects and Legal Obligations [Line Items]
Valuation allowances and reserves | $						$ 9.6
Hawaiian Electric | Kapolei Petroleum Contamination | James Campbell Company
Regulatory Projects and Legal Obligations [Line Items]
Incurred remediation costs | $	$ 1.2						$ 0.8
Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
Number of power purchase agreements (PPAs) | agreement		1				4
Power purchase capacity excluding agreements with smaller IPPs						362.2
Notice period for Endangered Species Act			60 days
Hawaiian Electric Company, Inc. and Subsidiaries | Stage 1 And 2 Renewable PPAs
Regulatory Projects and Legal Obligations [Line Items]
Purchase commitment, minimum power volume required to be purchased						105
Total contracted PV capacity (in megawatts)						985
Long-term contract for purchase of electric power, estimated annual cost | $						$ 40.0
PPAs beginning commercial operations | contract						3
Number of power purchase agreements (PPAs) | agreement						4