Shareholders' equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
AOCI Attributable to Parent [Roll Forward]
Beginning balance	$ 1,479,089	$ 2,344,841	$ 2,202,499
Current period other comprehensive income (loss) and reclassifications, net of taxes	(123)	3,184	46,678
Discontinued operations		289,627
Ending balance	1,605,919	1,479,089	2,344,841
Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	1,156,955	2,409,110	2,344,170
Current period other comprehensive income (loss) and reclassifications, net of taxes	(146)	(63)	(12)
Ending balance	1,583,399	1,156,955	2,409,110
AOCI
AOCI Attributable to Parent [Roll Forward]
Beginning balance	3,461	(289,350)	(336,028)
Current period other comprehensive income (loss) and reclassifications, net of taxes	(123)	3,184	46,678
Ending balance	3,338	3,461	(289,350)
AOCI | Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,786	2,849	2,861
Current period other comprehensive income (loss) and reclassifications, net of taxes	(146)	(63)	(12)
Ending balance	2,640	2,786	2,849
Net unrealized gains (losses) on securities
AOCI Attributable to Parent [Roll Forward]
Beginning balance	0	(282,963)	(328,904)
Current period other comprehensive income (loss) and reclassifications, net of taxes	0	1,785	45,941
Discontinued operations		281,178
Ending balance	0	0	(282,963)
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,120	1,638	1,991
Current period other comprehensive income (loss) and reclassifications, net of taxes	(1,520)	482	(353)
Discontinued operations		0
Ending balance	600	2,120	1,638
Retirement benefit plans
AOCI Attributable to Parent [Roll Forward]
Beginning balance	1,341	(8,025)	(9,115)
Current period other comprehensive income (loss) and reclassifications, net of taxes	1,397	917	1,090
Discontinued operations		8,449
Ending balance	2,738	1,341	(8,025)
Retirement benefit plans | Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,786	2,849	2,861
Current period other comprehensive income (loss) and reclassifications, net of taxes	(146)	(63)	(12)
Discontinued operations		0
Ending balance	$ 2,640	$ 2,786	$ 2,849