Shareholders' equity - Reclassification out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	$ (938,383)	$ (901,873)	$ (2,732,901)	$ (2,725,795)
Interest expense	32,085	32,629	96,076	91,259
Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	3,403	3,676	9,702	11,083
Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	(829,617)	(794,987)	(2,410,526)	(2,419,539)
Total reclassifications	82,087	(43,959)	1,271,262	(137,265)
Hawaiian Electric Company, Inc. and Subsidiaries | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	2	(77)	(93)	(166)
Amortization of unrealized holding losses on held-to-maturity securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	3,366	3,699	9,740	11,065
Net realized gains on derivatives qualifying as cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	(52)	(47)	(151)	(143)
Amortization of prior service credit and net gains recognized during the period in net periodic benefit cost | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(1,244)	(446)	(2,138)	(1,160)
Amortization of prior service credit and net gains recognized during the period in net periodic benefit cost | Hawaiian Electric Company, Inc. and Subsidiaries | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(1,331)	(547)	(2,344)	(1,487)
Impact of D&Os of the PUC included in regulatory assets | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	1,333	470	2,251	1,321
Impact of D&Os of the PUC included in regulatory assets | Hawaiian Electric Company, Inc. and Subsidiaries | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	$ 1,333	$ 470	$ 2,251	$ 1,321