v3.26.1
Credit agreements and long-term debt - Schedule of Long-Term Debt (Details) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Debt Instrument [Line Items]    
Less current portion long-term debt, net of unamortized debt issuance cost $ 0 $ (124,959)
Long-term debt, net 2,265,630 2,285,016
All other    
Debt Instrument [Line Items]    
Less unamortized debt issuance costs (539) (596)
Long-term debt, net 207,199 227,142
Hawaiian Electric Company, Inc. and Subsidiaries    
Debt Instrument [Line Items]    
Less unamortized debt issuance costs (11,569) (12,167)
Less current portion long-term debt, net of unamortized debt issuance cost 0 (124,959)
Long-term debt, net 2,058,431 2,057,874
HEI 2.48%-6.10% senior notes due 2028-2052 | Senior Notes | All other    
Debt Instrument [Line Items]    
Aggregate principal amount, issued 207,738 $ 207,738
HEI revolving credit facility SOFR + 2.50%, due 2030 | Line of Credit    
Debt Instrument [Line Items]    
Weighted average interest rate (as percent)   6.32%
HEI revolving credit facility SOFR + 2.50%, due 2030 | Line of Credit | All other    
Debt Instrument [Line Items]    
Aggregate principal amount, issued $ 0 $ 20,000
Line of credit facility basis point spread (as percent) 2.50%  
Special purpose revenue bonds and unsecured senior notes | Hawaiian Electric Company, Inc. and Subsidiaries    
Debt Instrument [Line Items]    
Aggregate principal amount, issued $ 2,070,000 2,195,000
Mahipapa Non-Recourse Loans | Term Loan    
Debt Instrument [Line Items]    
Aggregate principal amount, issued $ 54,600 $ 54,000
Minimum | HEI 2.48%-6.10% senior notes due 2028-2052 | Senior Notes    
Debt Instrument [Line Items]    
Stated interest rate (as percent) 2.48%  
Maximum | HEI 2.48%-6.10% senior notes due 2028-2052 | Senior Notes    
Debt Instrument [Line Items]    
Stated interest rate (as percent) 6.10%