Cash flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Supplemental disclosures of cash flow information
Interest paid to non-affiliates, net of amounts capitalized	$ 21	$ 10
Supplemental disclosures of noncash activities
Unpaid invoices and accruals for capital expenditures, balance, end of period (investing)	50	24
Increase related to an acquisition (investing)	0	15
Right-of-use assets obtained in exchange for finance lease obligations (financing)	40	0
Right-of-use assets obtained in exchange for operating lease obligations (investing)	1	35
Common stock issued (gross) for director and executive/management compensation (financing)	7	8
Obligations to fund low income housing investments (investing)	7	0
Unsettled trades to purchase investment securities (investing)	0	25
Other receivable related to pending sales proceeds from the sale of an equity-method investment (investing)	0	9
Hawaiian Electric Company, Inc. and Subsidiaries
Supplemental disclosures of cash flow information
Interest paid to non-affiliates, net of amounts capitalized	6	6
Income taxes paid (including refundable credits)	3	0
Supplemental disclosures of noncash activities
Unpaid invoices and accruals for capital expenditures, balance, end of period (investing)	48	21
Increase related to an acquisition (investing)	0	15
Right-of-use assets obtained in exchange for finance lease obligations (financing)	40	0
Right-of-use assets obtained in exchange for operating lease obligations (investing)	$ 0	$ 32