v3.26.1
Income taxes (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2026
Jun. 30, 2025
Income Tax Contingency [Line Items]      
Effective income tax, percent   24.00% 27.00%
Tax expense $ 0.3    
Hawaiian Electric Company, Inc. and Subsidiaries      
Income Tax Contingency [Line Items]      
Effective income tax, percent   24.00% 21.00%