Income taxes - Components of Income Taxes Attributable to Net Income for Common Stock (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Federal
Current	$ 51,455	$ 23,207	$ 28,736
Deferred	(11,689)	(4,215)	(4,353)
Deferred tax credits, net	4,611	10,979	13,410
Federal taxes	44,377	29,971	37,793
State
Current	12,119	8,430	10,472
Deferred	6,290	2,509	(10,732)
Deferred tax credits, net	21	0	14,104
State taxes	18,430	10,939	13,844
Total	62,807	40,910	51,637
Hawaiian Electric Company, Inc. and Subsidiaries
Federal
Current	42,794	31,950	21,751
Deferred	(12,109)	(5,408)	(7,793)
Deferred tax credits, net	302	1,549	13,155
Federal taxes	30,987	28,091	27,113
State
Current	4,861	3,768	5,579
Deferred	8,279	8,559	(8,491)
Deferred tax credits, net	21	0	14,104
State taxes	13,161	12,327	11,192
Total	$ 44,148	$ 40,418	$ 38,305