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Long-term debt - Schedule of Long-Term Debt and Maturities (Details) - USD ($)
 12 Months Ended
Jul. 01, 2023
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Debt Instrument [Line Items]        
Less unamortized debt issuance costs and debt discount   $ (8,097,000) $ (8,165,000)  
Long-term debt, net—other than bank   2,842,429,000 2,384,980,000  
Hawaiian Electric Company, Inc. and Subsidiaries        
Debt Instrument [Line Items]        
Gross long-term debt   1,942,000,000 1,692,000,000  
Long-term debt of Utilities, net of unamortized debt issuance costs        
Debt Instrument [Line Items]        
Long-term debt, net—other than bank   1,934,277,000 1,684,816,000  
Senior notes | Hawaiian Electric Company, Inc. and Subsidiaries        
Debt Instrument [Line Items]        
Gross long-term debt   1,200,000,000 1,150,000,000  
Senior notes | HEI 3.99% senior notes, paid in 2023        
Debt Instrument [Line Items]        
Gross long-term debt   $ 0 50,000,000  
Debt instrument, stated interest rate (as percent)   3.99%    
Senior notes | HEI 4.58% senior notes, due 2025        
Debt Instrument [Line Items]        
Gross long-term debt   $ 50,000,000 50,000,000  
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   $ 100,000,000 100,000,000  
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   $ 24,000,000 24,000,000  
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   $ 30,000,000 30,000,000  
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   $ 39,000,000 0  
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   $ 50,000,000 50,000,000  
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   $ 51,000,000 51,000,000  
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   $ 25,000,000 25,000,000  
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   $ 30,000,000 30,000,000  
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   $ 75,000,000 75,000,000  
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   $ 61,000,000 0  
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   $ 35,000,000 35,000,000  
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   $ 20,000,000 20,000,000  
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   $ 20,000,000 20,000,000  
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   $ 44,855,000 49,048,000  
Debt instrument, stated interest rate (as percent)   4.02%    
Debt collateralized by property, plant and equipment   $ 187,000,000    
Term Loan | Mauō 4.91% non-recourse loan, due 2034 to 2035        
Debt Instrument [Line Items]        
Gross long-term debt   $ 16,962,000 17,692,000  
Debt instrument, stated interest rate (as percent)   4.91%    
Term Loan | Ka`ie`ie Waho 2.79% non-recourse loan, due 2031        
Debt Instrument [Line Items]        
Gross long-term debt   $ 9,727,000 10,936,000  
Debt instrument, stated interest rate (as percent)   2.79%    
Term Loan | Mahipapa 1.90% non-recourse loan, due 2034 to 2036        
Debt Instrument [Line Items]        
Gross long-term debt   $ 53,743,000 58,869,000  
Debt instrument, stated interest rate (as percent)   1.90%    
Term Loan | Mahipapa 5.625% non-recourse loan, due 2027        
Debt Instrument [Line Items]        
Gross long-term debt   $ 578,000 724,000  
Debt instrument, stated interest rate (as percent)   5.625%    
Unsecured Debt | Hawaiian Electric Company, Inc. and Subsidiaries        
Debt Instrument [Line Items]        
Gross long-term debt   $ 1,400,000,000 1,150,000,000  
Unsecured Debt | Mauo SOFR + 1.375% loan, due 2023        
Debt Instrument [Line Items]        
Gross long-term debt   $ 5,384,000 11,060,000  
Maximum aggregate principal amount       $ 50,500,000
Unsecured Debt | Mauo SOFR + 1.375% loan, due 2023 | SOFR        
Debt Instrument [Line Items]        
Line of credit facility basis point spread   1.475%    
Unsecured Debt | Mauo SOFR + 1.375% loan, due 2023 | Secured Overnight Financing Rate (SOFR), Excluding Replacement Rate Adjustment        
Debt Instrument [Line Items]        
Line of credit facility basis point spread 1.375%      
Unsecured Debt | Mauo SOFR + 1.375% loan, due 2023 | Secured Overnight Financing Rate (SOFR), Replacement Rate Adjustment        
Debt Instrument [Line Items]        
Line of credit facility basis point spread 0.10%      
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027        
Debt Instrument [Line Items]        
Gross long-term debt   $ 175,000,000 $ 0  
Weighted average interest rate (as percent)   7.19%    
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027 | SOFR        
Debt Instrument [Line Items]        
Line of credit facility basis point spread   1.80%    
Line of credit facility | HEI revolving credit facility SOFR + 1.80%, due 2026 to 2027 | 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 + 1.80%, due 2026 to 2027 | 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 + 1.80%, due 2026 to 2027 | Secured Overnight Financing Rate (SOFR), Additional Adjustment        
Debt Instrument [Line Items]        
Line of credit facility basis point spread   0.10%