Electric utility segment - Asset Retirement Obligations (Details) - Hawaiian Electric Company, Inc. and Subsidiaries - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Regulatory Projects and Legal Obligations [Line Items]
ARO, recognition impact on earnings	$ 0
Changes in the asset retirement obligation liability
Balance at the beginning of the period	12,009,000	$ 11,548,000
Accretion expense	484,000	463,000
Liabilities incurred	0	0
Liabilities settled	(1,000)	(2,000)
Balance at the end of the period	$ 12,492,000	$ 12,009,000