v3.26.1
Credit agreements and long-term debt - Schedule of Line of Credit Facilities (Details) - Revolving Credit Facility - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Line of Credit Facility [Line Items]    
Capacity $ 850 $ 840
Outstanding 0 20
Undrawn 850 820
Hawaiian Electric Company, Inc. and Subsidiaries    
Line of Credit Facility [Line Items]    
Capacity 625 615
Outstanding 0 0
Undrawn 625 615
Unsecured revolving line of credit    
Line of Credit Facility [Line Items]    
Capacity 300 300
Outstanding 0 20
Undrawn 300 280
Unsecured revolving line of credit | Hawaiian Electric Company, Inc. and Subsidiaries    
Line of Credit Facility [Line Items]    
Capacity 300 300
Outstanding 0 0
Undrawn 300 300
ABL Facility | Hawaiian Electric Company, Inc. and Subsidiaries    
Line of Credit Facility [Line Items]    
Capacity 250 240
Outstanding 0 0
Undrawn 250 240
Borrowing from HEI - standing commitment letter | Hawaiian Electric Company, Inc. and Subsidiaries    
Line of Credit Facility [Line Items]    
Capacity 75 75
Outstanding 0 0
Undrawn $ 75 $ 75