Electric utility segment - Unconsolidated variable interest entities (Details)	9 Months Ended
	Sep. 30, 2020 entity agreement
Power purchase agreement
Number of IPPs	3
Hawaiian Electric Company
Power purchase agreement
Number of power purchase agreements (PPAs) (in agreements) | agreement	4
Number of firm capacity producers declining to provide financial information to determine primary beneficiary status (in entities)	2
Minimum potential number of IPP entities consolidated into company in the future (in entities)	1