Electric utility segment - Related-Party Transactions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Hawaiian Electric Company, Inc. and Subsidiaries
Related Party Transaction [Line Items]
Amount charged to subsidiaries for general management and administrative services	$ 5,500,000	$ 5,200,000	$ 5,600,000
Hawaiian Electric Company, Inc. and Subsidiaries | Interest Charged
Related Party Transaction [Line Items]
Amount charged to subsidiaries for general management and administrative services	0	0
Hawaiian Electric Company, Inc. and Subsidiaries | Hawaiian Electric
Related Party Transaction [Line Items]
Short-term borrowings	0	0
Hawaii Electric Light | Hamakua Energy
Related Party Transaction [Line Items]
Amount charged to subsidiaries for general management and administrative services	$ 35,000,000	$ 71,000,000	$ 66,000,000