Cash flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Supplemental disclosures of cash flow information
Interest paid to non-affiliates, net of amounts capitalized	$ 75	$ 47
Income taxes paid (including refundable credits)	28	14
Income taxes refunded (including refundable credits)	1	2
Supplemental disclosures of noncash activities
Estimated fair value of noncash contributions in aid of construction (investing)	6	1
Unpaid invoices and accruals for capital expenditures, balance, end of period (investing)	50	25
Increase related to an acquisition (investing)	0	15
Right-of-use assets obtained in exchange for finance lease obligations (financing)	76	0
Right-of-use assets obtained in exchange for operating lease obligations (investing)	1	40
Common stock issued (gross) for director and executive/management compensation (financing)	8	9
Obligations to fund low income housing investments (investing)	7	0
Loans transferred from held for investment to held for sale (investing)	72	0
Transfer of retail repurchase agreements to deposit liabilities (financing)	98	0
Hawaiian Electric Company, Inc. and Subsidiaries
Supplemental disclosures of cash flow information
Interest paid to non-affiliates, net of amounts capitalized	33	34
Income taxes paid (including refundable credits)	38	27
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	1
Unpaid invoices and accruals for capital expenditures, balance, end of period (investing)	49	22
Increase related to an acquisition (investing)	0	15
Right-of-use assets obtained in exchange for finance lease obligations (financing)	76	0
Right-of-use assets obtained in exchange for operating lease obligations (investing)	$ 0	$ 37