Electric utility segment - Power Purchase Agreements (Details) - Hawaiian Electric - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	$ 672	$ 794	$ 670
Kalaeloa
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	298	342	204
AES Hawaii
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	0	82	130
HPOWER
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	70	73	70
Hamakua Energy
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	71	66	53
Puna Geothermal Venture
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	38	48	29
Wind IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	125	119	124
Solar IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	72	57	50
Other IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power		$ 7	$ 10
Other Independent Power Producers, Including Netting
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	$ (2)