Income taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets
Regulatory liabilities, excluding amounts attributable to property, plant and equipment	$ 78,884	$ 82,488
Lease liabilities	113,968	45,016
Retirement benefits	23,502	7,692
Revenue taxes	49,522	51,392
Allowance for bad debts	22,942	22,734
Available-for-sale investments	103,587	120,405
Other	40,051	39,399
Total deferred tax assets	432,456	369,126
Deferred tax liabilities
Property, plant and equipment related	533,286	511,832
Lease right-of-use assets	113,498	44,461
Regulatory assets, excluding amounts attributable to property, plant and equipment	21,872	22,183
Retirement benefits	0	0
Other	61,754	53,112
Total deferred tax liabilities	730,410	631,588
Net deferred income tax liability	297,954	262,462
Deferred tax assets, tax credit carryforwards	6,000
Hawaiian Electric Company, Inc. and Subsidiaries
Deferred tax assets
Regulatory liabilities, excluding amounts attributable to property, plant and equipment	78,884	82,488
Lease liabilities	107,409	37,472
Retirement benefits	23,247	6,852
Revenue taxes	49,522	51,392
Allowance for bad debts	1,646	2,195
Available-for-sale investments	0	0
Other	19,171	20,287
Total deferred tax assets	279,879	200,686
Deferred tax liabilities
Property, plant and equipment related	513,064	497,929
Lease right-of-use assets	107,409	37,472
Regulatory assets, excluding amounts attributable to property, plant and equipment	21,872	22,183
Retirement benefits	0	0
Other	36,535	27,532
Total deferred tax liabilities	678,880	585,116
Net deferred income tax liability	399,001	$ 384,430
State and Local Jurisdiction
Deferred tax liabilities
Tax credit carryforward	$ 8,100