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Electric utility segment - Unconsolidated variable interest entities (Details)
1 Months Ended 3 Months Ended 9 Months Ended
Jun. 30, 2022
MW
Jun. 30, 2021
MW
Mar. 31, 2021
MW
Sep. 30, 2022
entity
agreement
Power purchase agreement        
Number of IPPs (in entities) | entity       2
Puna Geothermal Venture Power Purchase Agreement        
Power purchase agreement        
Firm capacity volume (in megawatts) | MW 25.7 23.9 13.0  
Hawaiian Electric Company        
Power purchase agreement        
Number of power purchase agreements (PPAs) (in agreements) | agreement       4