Electric utility segment - Regulatory assets for COVID-19 related costs (Details) - Hawaiian Electric Company, Inc. and Subsidiaries - USD ($) $ in Millions		1 Months Ended	3 Months Ended
	Jun. 09, 2022	Dec. 31, 2021	Mar. 31, 2023
Regulatory Projects and Legal Obligations [Line Items]
Recovery of deferral costs	$ 27.8
Recovery of deferral costs period	3 years
COVID-19
Regulatory Projects and Legal Obligations [Line Items]
Customer bill forgiveness		$ 2.0
Public utilities in regulatory assets			$ 9.6