Electric utility segment - Major Customers (Details) - Various federal government agencies - Operating revenues - Customer concentration - Hawaiian Electric Company, Inc. and Subsidiaries - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Major customers
Operating revenues percentage	12.00%	12.00%	11.00%
Operating revenues amount	$ 376	$ 393	$ 267