v3.26.1
Shareholders' equity - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Mar. 31, 2026
Jun. 30, 2025
Mar. 31, 2025
Jun. 30, 2026
Jun. 30, 2025
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance $ 1,637,369 $ 1,605,919 $ 1,505,876 $ 1,479,089 $ 1,605,919 $ 1,479,089
Current period other comprehensive loss (75) (74) (306) (460) (149) (766)
Ending balance 1,762,887 1,637,369 1,534,432 1,505,876 1,762,887 1,534,432
AOCI            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 3,264 3,338 3,001 3,461 3,338 3,461
Current period other comprehensive loss (75) (74) (306) (460)    
Ending balance 3,189 3,264 2,695 3,001 3,189 2,695
Unrealized gains (losses) on derivatives            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance   600   2,120 600 2,120
Current period other comprehensive loss         (106) (720)
Ending balance 494   1,400   494 1,400
Retirement benefit plans            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance   2,738   1,341 2,738 1,341
Current period other comprehensive loss         (43) (46)
Ending balance 2,695   1,295   2,695 1,295
Hawaiian Electric Company, Inc. and Subsidiaries            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 1,608,695 1,583,399 1,492,244 1,156,955 1,583,399 1,156,955
Current period other comprehensive loss (47) (47) (47) (47) (94) (94)
Ending balance 1,866,258 1,608,695 1,521,617 1,492,244 1,866,258 1,521,617
Hawaiian Electric Company, Inc. and Subsidiaries | AOCI            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance 2,593 2,640 2,739 2,786 2,640 2,786
Current period other comprehensive loss (47) (47) (47) (47)    
Ending balance 2,546 2,593 2,692 2,739 2,546 2,692
Hawaiian Electric Company, Inc. and Subsidiaries | Retirement benefit plans            
AOCI Attributable to Parent, Net of Tax [Roll Forward]            
Beginning balance   $ 2,640   $ 2,786 2,640 2,786
Current period other comprehensive loss         (94) (94)
Ending balance $ 2,546   $ 2,692   $ 2,546 $ 2,692