Electric utility segment - Power Purchase Agreements (Details) - Hawaiian Electric - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	$ 703	$ 672	$ 794
Kalaeloa
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	291	298	342
AES Hawaii
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	0	0	82
HPOWER
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	74	70	73
Hamakua Energy
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	35	71	66
Puna Geothermal Venture
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	56	38	48
Kapolei Energy Storage
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	24	0	0
Wind IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	130	125	119
Solar IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	84	72	57
Other IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power			$ 7
Other Independent Power Producers, Including Netting
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	$ 9	$ (2)