Shareholders' equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
AOCI Attributable to Parent [Roll Forward]
Beginning balance	$ 2,344,841	$ 2,202,499	$ 2,390,884
Current period other comprehensive income (loss) and reclassifications, net of taxes	3,184	46,678	(283,495)
Discontinued operations	289,627
Ending balance	1,479,089	2,344,841	2,202,499
Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,409,110	2,344,170	2,261,899
Current period other comprehensive income (loss) and reclassifications, net of taxes	(63)	(12)	6,141
Ending balance	1,156,955	2,409,110	2,344,170
AOCI
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(289,350)	(336,028)	(52,533)
Current period other comprehensive income (loss) and reclassifications, net of taxes	3,184	46,678	(283,495)
Ending balance	3,461	(289,350)	(336,028)
AOCI | Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,849	2,861	(3,280)
Current period other comprehensive income (loss) and reclassifications, net of taxes	(63)	(12)	6,141
Ending balance	2,786	2,849	2,861
Net unrealized gains (losses) on securities
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(282,963)	(328,904)	(32,037)
Current period other comprehensive income (loss) and reclassifications, net of taxes	1,785	45,941	(296,867)
Discontinued operations	281,178
Ending balance	0	(282,963)	(328,904)
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent [Roll Forward]
Beginning balance	1,638	1,991	(3,638)
Current period other comprehensive income (loss) and reclassifications, net of taxes	482	(353)	5,629
Discontinued operations	0
Ending balance	2,120	1,638	1,991
Retirement benefit plans
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(8,025)	(9,115)	(16,858)
Current period other comprehensive income (loss) and reclassifications, net of taxes	917	1,090	7,743
Discontinued operations	8,449
Ending balance	1,341	(8,025)	(9,115)
Retirement benefit plans | Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,849	2,861	(3,280)
Current period other comprehensive income (loss) and reclassifications, net of taxes	(63)	(12)	6,141
Discontinued operations	0
Ending balance	$ 2,786	$ 2,849	$ 2,861