Electric utility segment - Schedule of Power Purchase Agreements (Details) - Hawaiian Electric - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	$ 678	$ 703	$ 672
Kalaeloa
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	274	291	298
HPOWER
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	71	74	70
Hamakua Energy
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	37	35	71
Puna Geothermal Venture
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	41	56	38
Kapolei Energy Storage
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	24	24	0
Wind IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	116	130	125
Solar IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	110	84	72
Other IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power	$ 5	$ 9
Other IPPs, Including Netting
Regulatory Projects and Legal Obligations [Line Items]
Purchased power			$ (2)