Shareholders' equity - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
AOCI Attributable to Parent [Roll Forward]
Beginning balance	$ 2,390,884	$ 2,337,502	$ 2,280,260
Current period other comprehensive income (loss) and reclassifications, net of taxes	(283,495)	(51,269)	18,775
Ending balance	2,202,499	2,390,884	2,337,502
Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	2,261,899	2,141,918	2,047,352
Current period other comprehensive income (loss) and reclassifications, net of taxes	6,141	(361)	(1,640)
Ending balance	2,344,170	2,261,899	2,141,918
AOCI
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(52,533)	(1,264)	(20,039)
Current period other comprehensive income (loss) and reclassifications, net of taxes	(283,495)	(51,269)	18,775
Ending balance	(336,028)	(52,533)	(1,264)
AOCI | Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(3,280)	(2,919)	(1,279)
Current period other comprehensive income (loss) and reclassifications, net of taxes	6,141	(361)	(1,640)
Ending balance	2,861	(3,280)	(2,919)
Net unrealized gains (losses) on securities
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(32,037)	19,986	2,481
Current period other comprehensive income (loss) and reclassifications, net of taxes	(296,867)	(52,023)	17,505
Ending balance	(328,904)	(32,037)	19,986
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(3,638)	(3,363)	(1,613)
Current period other comprehensive income (loss) and reclassifications, net of taxes	5,629	(275)	(1,750)
Ending balance	1,991	(3,638)	(3,363)
Retirement benefit plans
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(16,858)	(17,887)	(20,907)
Current period other comprehensive income (loss) and reclassifications, net of taxes	7,743	1,029	3,020
Ending balance	(9,115)	(16,858)	(17,887)
Retirement benefit plans | Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(3,280)	(2,919)	(1,279)
Current period other comprehensive income (loss) and reclassifications, net of taxes	6,141	(361)	(1,640)
Ending balance	$ 2,861	$ (3,280)	$ (2,919)