Shareholders' equity - Reclassification out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Reclassifications out of accumulated other comprehensive income/(loss)
Gain on sale of investment securities, net	$ 0	$ 0	$ (8,123)	$ (528)
Interest expense	26,626	23,477	75,940	70,530
Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	356	63	818	72
Hawaiian Electric Company, Inc. and Subsidiaries
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	(50,262)	(50,840)	(141,804)	(137,097)
Hawaiian Electric Company, Inc. and Subsidiaries | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Total reclassifications	108	106	210	175
Net realized gains on securities included in net income | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Gain on sale of investment securities, net	0	0	0	(387)
Net realized losses on derivatives qualifying as cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Reclassifications out of accumulated other comprehensive income/(loss)
Interest expense	53	9	161	9
Amortization of prior service credit and net losses 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	5,606	2,853	10,229	14,871
Amortization of prior service credit and net losses 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	5,411	2,905	9,782	14,596
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	(5,303)	(2,799)	(9,572)	(14,421)
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	$ (5,303)	$ (2,799)	$ (9,572)	$ (14,421)