Cash flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Supplemental disclosures of cash flow information
Interest paid to non-affiliates, net of amounts capitalized	$ 59	$ 61
Income taxes paid (including refundable credits)	26	34
Income taxes refunded (including refundable credits)	2	0
Supplemental disclosures of noncash activities
Estimated fair value of noncash contributions in aid of construction (investing)	6	5
Unpaid invoices and accruals for capital expenditures, balance, end of period (investing)	34	30
Increase related to an acquisition (investing)	15	0
Right-of-use assets obtained in exchange for finance lease obligations (financing)	48	0
Right-of-use assets obtained in exchange for operating lease obligations (investing)	48	44
Property, plant, equipment and other assets received in exchange for the assumption of debt associated with a business acquisition (investing)	68	0
Debt, lease liabilities and other liabilities assumed in business acquisition (financing)	68	0
Common stock issued (gross) for director and executive/management compensation (financing)	10	7
Obligations to fund low income housing investments (investing)	9	9
Loans transferred from held for investment to held for sale (investing)	0	62
Hawaiian Electric Company, Inc. and Subsidiaries
Supplemental disclosures of cash flow information
Interest paid to non-affiliates, net of amounts capitalized	40	43
Income taxes paid (including refundable credits)	46	20
Supplemental disclosures of noncash activities
Estimated fair value of noncash contributions in aid of construction (investing)	6	5
Unpaid invoices and accruals for capital expenditures, balance, end of period (investing)	31	27
Increase related to an acquisition (investing)	15	0
Right-of-use assets obtained in exchange for finance lease obligations (financing)	48	0
Right-of-use assets obtained in exchange for operating lease obligations (investing)	$ 44	$ 44