Electric utility segment - Power Purchase Agreements (Details) $ in Thousands		1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 21, 2023 MW	Oct. 31, 2021	Jul. 31, 2018 MW	Feb. 28, 2018 USD ($) agreement MW	May 31, 2012 MW	Sep. 30, 2023 USD ($) project	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) project	Sep. 30, 2022 USD ($)	Dec. 31, 1988 MW	Dec. 31, 2022 USD ($)
Regulatory Projects and Legal Obligations [Line Items]
Finance lease liabilities						$ 122,320		$ 122,320			$ 48,709
Kalaeloa
Regulatory Projects and Legal Obligations [Line Items]
Purchase commitment, extension period (in years)		10 years
Stage 1 Renewable PPAs
Regulatory Projects and Legal Obligations [Line Items]
Number of power purchase agreements (PPAs) (in agreements) | agreement				8
Minimum power volume required (in megawatts) | MW	30			274.5
Estimated annual cost				$ 71,200
Long term purchase commitments, number of projects | project						3		3
Finance lease liabilities						$ 124,000		$ 124,000
Financing lease right-of-use assets						124,000		124,000
Total contracted PV capacity (in megawatts) | MW	120
Hu Honua Bioenergy, LLC
Regulatory Projects and Legal Obligations [Line Items]
Minimum power volume required (in megawatts) | MW					21.5
Molokai New Energy Partners
Regulatory Projects and Legal Obligations [Line Items]
Total contracted PV capacity (in megawatts) | MW			4.88
Total contracted battery energy storage system capacity | MW			3
Maximum power volume to be delivered (in megawatts) | MW			2.64
Hawaiian Electric, Parent
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						178,000	$ 225,000	499,000	$ 607,000
Hawaiian Electric, Parent | Kalaeloa
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						77,000	101,000	211,000	244,000
Increased power purchase commitment capacity (in megawatts) | MW										208
Hawaiian Electric, Parent | AES Hawaii
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						0	21,000	0	82,000
Hawaiian Electric, Parent | HPOWER
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						17,000	18,000	51,000	56,000
Hawaiian Electric, Parent | Hamakua Energy
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						13,000	16,000	52,000	46,000
Hawaiian Electric, Parent | Puna Geothermal Venture
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						7,000	13,000	24,000	37,000
Hawaiian Electric, Parent | Wind IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						42,000	37,000	99,000	93,000
Hawaiian Electric, Parent | Solar IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						21,000	18,000	57,000	44,000
Hawaiian Electric, Parent | Other IPPs
Regulatory Projects and Legal Obligations [Line Items]
Purchased power						$ 1,000	$ 1,000	$ 5,000	$ 5,000