Electric utility segment - Purchases from IPPs (Details) - Hawaiian Electric, Parent - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	$ 181	$ 168	$ 341	$ 321
Kalaeloa
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	79	67	145	134
HPOWER
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	16	16	33	34
Puna Geothermal Venture
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	14	9	27	17
Hamakua Energy
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	5	19	16	39
Kapolei Energy Storage
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	6	0	12	0
Wind IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	37	33	67	57
Solar IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	21	22	36	36
Other IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	$ 3	$ 2	$ 5	$ 4