Electric utility segment - Commitments and contingencies (Details) $ in Thousands					1 Months Ended			9 Months Ended	12 Months Ended
	Jun. 07, 2024 USD ($) MW	May 31, 2024 USD ($) MW	Mar. 28, 2024 USD ($) MW	Nov. 16, 2023 defendant	Jan. 31, 2024	Jul. 31, 2018 MW	May 31, 2012 MW	Sep. 30, 2024 USD ($) agreement MW	Dec. 31, 2022 USD ($)	Dec. 31, 2019 agreement	Dec. 31, 2023 USD ($)
Long-term Purchase Commitment [Line Items]
Finance lease liabilities								$ 441,089			$ 339,040
Operating lease right-of-use assets								$ 84,645			94,905
Environmental loss contingency, statement of financial position, not disclosed								reserve account balance
Purchase obligation											1,700,000
Maui Electric
Long-term Purchase Commitment [Line Items]
Additional accrued investigation and estimated cleanup costs								$ 2,500
Hawaiian Electric, Parent | PCB Contamination
Long-term Purchase Commitment [Line Items]
Valuation allowances and reserves								9,500
Hawaiian Electric Company, Inc. and Subsidiaries
Long-term Purchase Commitment [Line Items]
Operating lease right-of-use assets								61,007			$ 71,877
Notice period, pre-cursor to citizen's suit					60 days
Number of power purchase agreements (PPAs) (in agreements) | agreement										7
Hu Honua Bioenergy, LLC
Long-term Purchase Commitment [Line Items]
Minimum power volume required (in megawatts) | MW							21.5
Number of defendants | defendant				3
Molokai New Energy Partners
Long-term Purchase Commitment [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
James Campbell Company | Hawaiian Electric, Parent | Kapolei Petroleum Contamination
Long-term Purchase Commitment [Line Items]
Environmental remediation expense									$ 1,400
AES Hawaii | Hawaiian Electric Company, Inc. and Subsidiaries
Long-term Purchase Commitment [Line Items]
Minimum power volume required (in megawatts) | MW	42	60	12.5
Total contracted PV capacity (in megawatts) | MW	168	240	50
Annual payment	$ 11,500	$ 13,200	$ 3,200
Finance lease liabilities								107,400
Operating lease right-of-use assets								$ 107,400
Stage 1 And 2 Renewable PPAs | Hawaiian Electric Company, Inc. and Subsidiaries
Long-term Purchase Commitment [Line Items]
Minimum power volume required (in megawatts) | MW								114.5
Total contracted PV capacity (in megawatts) | MW								458
Number of power purchase agreements (PPAs) (in agreements) | agreement								3