Electric utility segment - Regulatory Assets and Liabilities (Details) - Hawaiian Electric Company, Inc. and Subsidiaries - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Regulatory assets
Regulatory assets	$ 281,319	$ 294,804
Regulatory liabilities
Regulatory Liability	1,244,083	1,150,690
Cost of removal in excess of salvage value
Regulatory liabilities
Regulatory Liability	601,741	591,298
Income taxes
Regulatory liabilities
Regulatory Liability	292,036	303,225
Decoupling revenue balancing account and RAM
Regulatory liabilities
Regulatory Liability	5,498	5,995
Retirement benefit plans
Regulatory liabilities
Regulatory Liability	279,553	171,421
Solar tax credits
Regulatory liabilities
Regulatory Liability	46,661	49,507
ECRC and PPAC
Regulatory liabilities
Regulatory Liability	4,296	15,169
Enterprise Resource Planning (ERP) Benefits
Regulatory liabilities
Regulatory Liability	12,549	12,409
Other
Regulatory liabilities
Regulatory Liability	$ 1,749	1,666
Minimum | Cost of removal in excess of salvage value
Regulatory liabilities
Authorized amortization or recovery periods (in years)	1 year
Minimum | Income taxes
Regulatory liabilities
Authorized amortization or recovery periods (in years)	35 years
Minimum | Decoupling revenue balancing account and RAM
Regulatory liabilities
Authorized amortization or recovery periods (in years)	1 year
Minimum | Solar tax credits
Regulatory liabilities
Authorized amortization or recovery periods (in years)	1 year
Minimum | Other
Regulatory liabilities
Remaining amortization or recovery periods (in years)	1 year
Maximum | Cost of removal in excess of salvage value
Regulatory liabilities
Authorized amortization or recovery periods (in years)	79 years
Maximum | Income taxes
Regulatory liabilities
Authorized amortization or recovery periods (in years)	1 year
Maximum | Solar tax credits
Regulatory liabilities
Authorized amortization or recovery periods (in years)	17 years
Current assets
Regulatory assets
Regulatory assets	$ 53,895	68,453
Long-term assets
Regulatory assets
Regulatory assets	227,424	226,351
Current liabilities
Regulatory liabilities
Regulatory Liability	26,568	36,559
Long-term liabilities
Regulatory liabilities
Regulatory Liability	1,217,515	1,114,131
Income taxes
Regulatory assets
Regulatory assets	$ 81,102	81,620
Income taxes | Minimum
Regulatory assets
Authorized amortization or recovery periods (in years)	1 year
Income taxes | Maximum
Regulatory assets
Authorized amortization or recovery periods (in years)	35 years
Retirement benefit plans (balance primarily varies with plans’ funded statuses)
Regulatory assets
Regulatory assets	$ 13,755	70,616
Maui windstorm and wildfire related costs (to be determined by PUC)
Regulatory assets
Regulatory assets	52,652	14,692
Retirement of Generating Units
Regulatory assets
Regulatory assets	$ 40,953	29,930
Authorized amortization or recovery periods (in years)	10 years
Right-Of-Use Assets
Regulatory assets
Regulatory assets	$ 19,105	9,067
Remaining amortization or recovery periods (in years)	25 years
ECRC and PPAC
Regulatory assets
Regulatory assets	$ 17,418	24,691
Authorized amortization or recovery periods (in years)	1 year
Regulatory liabilities
Remaining amortization or recovery periods (in years)	1 year
Vacation earned, but not yet taken
Regulatory assets
Regulatory assets	$ 13,950	14,585
Authorized amortization or recovery periods (in years)	1 year
Decoupling revenue balancing account and RAM
Regulatory assets
Regulatory assets	$ 9,829	19,002
Authorized amortization or recovery periods (in years)	1 year
Performance Incentive Mechanisms
Regulatory assets
Regulatory assets	$ 6,783	2,923
Authorized amortization or recovery periods (in years)	1 year
COVID-19 related costs (3 years)
Regulatory assets
Regulatory assets	$ 6,715	8,715
Authorized amortization or recovery periods (in years)	3 years
Other
Regulatory assets
Regulatory assets	$ 19,057	$ 18,963
Other | Minimum
Regulatory assets
Remaining amortization or recovery periods (in years)	1 year
Other | Maximum
Regulatory assets
Remaining amortization or recovery periods (in years)	35 years