Shareholders' equity - Reclassification out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	$ (901,873)	$ (1,042,197)	$ (2,725,795)	$ (2,722,872)
Interest expense	32,629	26,626	91,259	75,940
Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	3,676	356	11,083	818
Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Revenues	(794,987)	(955,971)	(2,419,539)	(2,483,636)
Total reclassifications	(43,959)	(50,262)	(137,265)	(141,804)
Hawaiian Electric Company, Inc. and Subsidiaries | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(77)	108	(166)	210
Net unrealized gains (losses) on available-for sale investment securities - 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	3,699	0	11,065	0
Net realized losses (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	(47)	53	(143)	161
Amortization of prior service credit and net losses (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	(446)	5,606	(1,160)	10,229
Amortization of prior service credit and net losses (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	(547)	5,411	(1,487)	9,782
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	470	(5,303)	1,321	(9,572)
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	$ 470	$ (5,303)	$ 1,321	$ (9,572)