Income taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Expense (Benefit) [Line Items]
Deferred tax assets, valuation allowance	$ 73,459	$ 0
Settlement from IRS examination	10,800	0	$ 0
Unrecognized tax benefits that would impact effective tax rate	5,200	13,800
Credit adjustments to interest expense on income taxes	300	1,300	400
Amount of accrued interest related to uncertain tax positions	2,300	1,900
Capital Loss From Sale Of Discontinued Operation
Income Tax Expense (Benefit) [Line Items]
Deferred tax assets, valuation allowance	73,500	0
Hawaiian Electric Company, Inc. and Subsidiaries
Income Tax Expense (Benefit) [Line Items]
Deferred tax assets, valuation allowance	0	0
Settlement from IRS examination	10,800	0	0
Credit adjustments to interest expense on income taxes	300	100	$ 100
Amount of accrued interest related to uncertain tax positions	$ 100	$ 400