Shareholders' equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent [Roll Forward]
Beginning balance	$ 2,202,499	$ 2,390,884	$ 2,337,502
Current period other comprehensive income (loss) and reclassifications, net of taxes	46,678	(283,495)	(51,269)
Ending balance	2,344,841	2,202,499	2,390,884
Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,344,170	2,261,899	2,141,918
Current period other comprehensive income (loss) and reclassifications, net of taxes	(12)	6,141	(361)
Ending balance	2,409,110	2,344,170	2,261,899
AOCI
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(336,028)	(52,533)	(1,264)
Current period other comprehensive income (loss) and reclassifications, net of taxes	46,678	(283,495)	(51,269)
Ending balance	(289,350)	(336,028)	(52,533)
AOCI | Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,861	(3,280)	(2,919)
Current period other comprehensive income (loss) and reclassifications, net of taxes	(12)	6,141	(361)
Ending balance	2,849	2,861	(3,280)
Net unrealized gains (losses) on securities
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(328,904)	(32,037)	19,986
Current period other comprehensive income (loss) and reclassifications, net of taxes	45,941	(296,867)	(52,023)
Ending balance	(282,963)	(328,904)	(32,037)
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent [Roll Forward]
Beginning balance	1,991	(3,638)	(3,363)
Current period other comprehensive income (loss) and reclassifications, net of taxes	(353)	5,629	(275)
Ending balance	1,638	1,991	(3,638)
Retirement benefit plans
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(9,115)	(16,858)	(17,887)
Current period other comprehensive income (loss) and reclassifications, net of taxes	1,090	7,743	1,029
Ending balance	(8,025)	(9,115)	(16,858)
Retirement benefit plans | Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,861	(3,280)	(2,919)
Current period other comprehensive income (loss) and reclassifications, net of taxes	(12)	6,141	(361)
Ending balance	$ 2,849	$ 2,861	$ (3,280)