Long-term debt - Schedule of Long-Term Debt and Maturities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Less unamortized debt issuance costs and debt discount	$ (596)	$ (6,681)
Less current portion long-term debt, net of unamortized debt issuance cost	(124,959)	(109,171)
Long-term debt, net—other than bank	2,285,016	2,690,387
Long-term debt of Utilities, net of unamortized debt issuance costs
Debt Instrument [Line Items]
Long-term debt, net—other than bank	2,182,833	1,901,214
Senior notes | HEI 4.58% senior notes, paid in 2025
Debt Instrument [Line Items]
Gross long-term debt	$ 0	50,000
Debt instrument, stated interest rate (as percent)	4.58%
Senior notes | HEI 4.72% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt	$ 37,096	100,000
Debt instrument, stated interest rate (as percent)	4.72%
Senior notes | HEI 2.82% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt	$ 8,903	24,000
Debt instrument, stated interest rate (as percent)	2.82%
Senior notes | HEI 2.48% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt	$ 11,129	30,000
Debt instrument, stated interest rate (as percent)	2.48%
Senior notes | HEI 6.04% senior notes, due 2028
Debt Instrument [Line Items]
Gross long-term debt	$ 14,467	39,000
Debt instrument, stated interest rate (as percent)	6.04%
Senior notes | HEI 2.98% senior notes, due 2030
Debt Instrument [Line Items]
Gross long-term debt	$ 18,548	50,000
Debt instrument, stated interest rate (as percent)	2.98%
Senior notes | HEI 3.15% senior notes, due 2031
Debt Instrument [Line Items]
Gross long-term debt	$ 18,919	51,000
Debt instrument, stated interest rate (as percent)	3.15%
Senior notes | HEI 2.78% senior notes, due 2031
Debt Instrument [Line Items]
Gross long-term debt	$ 9,274	25,000
Debt instrument, stated interest rate (as percent)	2.78%
Senior notes | HEI 2.98% senior notes, due 2032
Debt Instrument [Line Items]
Gross long-term debt	$ 11,129	30,000
Debt instrument, stated interest rate (as percent)	2.98%
Senior notes | HEI 5.43% senior notes, due 2032
Debt Instrument [Line Items]
Gross long-term debt	$ 27,822	75,000
Debt instrument, stated interest rate (as percent)	5.43%
Senior notes | HEI 6.10% senior notes, due 2033
Debt Instrument [Line Items]
Gross long-term debt	$ 22,629	61,000
Debt instrument, stated interest rate (as percent)	6.10%
Senior notes | HEI 5.43% senior notes, due 2034
Debt Instrument [Line Items]
Gross long-term debt	$ 12,984	35,000
Debt instrument, stated interest rate (as percent)	5.43%
Senior notes | HEI 3.74% senior notes, due 2051
Debt Instrument [Line Items]
Gross long-term debt	$ 7,419	20,000
Debt instrument, stated interest rate (as percent)	3.74%
Senior notes | HEI 3.94% senior notes, due 2052
Debt Instrument [Line Items]
Gross long-term debt	$ 7,419	20,000
Debt instrument, stated interest rate (as percent)	3.94%
Senior notes | Hāmākua Energy 4.02% non-recourse notes, due 2030
Debt Instrument [Line Items]
Gross long-term debt	$ 0	39,026
Debt instrument, stated interest rate (as percent)	4.02%
Term Loan | Mauō 5.07% non-recourse loan, due 2034 to 2035
Debt Instrument [Line Items]
Gross long-term debt	$ 0	20,795
Debt instrument, stated interest rate (as percent)	5.07%
Term Loan | Ka`ie`ie Waho 2.79% non-recourse loan, due 2031
Debt Instrument [Line Items]
Gross long-term debt	$ 0	8,517
Debt instrument, stated interest rate (as percent)	2.79%
Term Loan | Mahipapa 2.14% non-recourse loan, due 2034 to 2036
Debt Instrument [Line Items]
Gross long-term debt	$ 0	53,263
Debt instrument, stated interest rate (as percent)	2.14%
Term Loan | Mahipapa 5.625% non-recourse loan, due 2027
Debt Instrument [Line Items]
Gross long-term debt	$ 0	424
Debt instrument, stated interest rate (as percent)	5.625%
Term Loan | Mahipapa Non-Recourse Loans
Debt Instrument [Line Items]
Gross long-term debt	$ 54,000
Line of credit facility | HEI revolving credit facility SOFR + 2.50%, due 2030
Debt Instrument [Line Items]
Gross long-term debt	$ 20,000	$ 173,000
Weighted average interest rate (as percent)	6.32%	6.89%
Line of credit facility | HEI revolving credit facility SOFR + 2.50%, due 2030 | SOFR
Debt Instrument [Line Items]
Line of credit facility basis point spread	2.50%
Line of credit facility | HEI revolving credit facility SOFR + 2.50%, due 2030 | Secured Overnight Financing Rate (SOFR) Excluding Sustainability Margin And Additional Adjustments
Debt Instrument [Line Items]
Line of credit facility basis point spread	1.75%
Line of credit facility | HEI revolving credit facility SOFR + 2.50%, due 2030 | Secured Overnight Financing Rate (SOFR), Sustainability Margin Adjustment
Debt Instrument [Line Items]
Line of credit facility basis point spread	0.05%
Line of credit facility | HEI revolving credit facility SOFR + 2.50%, due 2030 | Secured Overnight Financing Rate (SOFR), Additional Adjustment
Debt Instrument [Line Items]
Line of credit facility basis point spread	0.10%