Electric utility segment - Unconsolidated variable interest entities (Details)	3 Months Ended
	Mar. 31, 2021 entity agreement MW
Power purchase agreement
Number of IPPs (in entities) | entity	3
Puna Geothermal Venture Power Purchase Agreement
Power purchase agreement
Firm capacity volume (in megawatts) | MW	13
Hawaiian Electric Company
Power purchase agreement
Number of power purchase agreements (PPAs) (in agreements) | agreement	5