Electric utility segment - Commitments and contingencies (Details) $ in Thousands				1 Months Ended		6 Months Ended
	Jul. 11, 2025 USD ($) MW	Mar. 25, 2025 USD ($) MW	Nov. 16, 2023 defendant	Jul. 31, 2018 MW	May 31, 2012 MW	Jun. 30, 2025 USD ($) agreement MW	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Long-term Purchase Commitment [Line Items]
Environmental loss contingency, statement of financial position, not disclosed						reserve account balance
Purchase obligation								$ 2,200,000
Operating lease right-of-use assets						$ 62,065		66,553
Maui Electric
Long-term Purchase Commitment [Line Items]
Additional accrued investigation and estimated cleanup costs						2,400
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						$ 60,943		$ 59,281
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
Stage1 And2 Renewable P P | Hawaiian Electric Company, Inc. and Subsidiaries
Long-term Purchase Commitment [Line Items]
Minimum power volume required (in megawatts) | MW		30				249.5
Total contracted PV capacity (in megawatts) | MW		120				1,563
Annual payment		$ 11,900
Operating lease right-of-use assets							$ 42,300
Finance lease liabilities							$ 42,300
Number of power purchase agreements (PPAs) (in agreements) | agreement						8
Hoohana Solar | Hawaiian Electric Company, Inc. and Subsidiaries | Subsequent Event
Long-term Purchase Commitment [Line Items]
Minimum power volume required (in megawatts) | MW	52
Total contracted PV capacity (in megawatts) | MW	208
Annual payment	$ 13,400
Hoohana Solar | Hawaiian Electric Company, Inc. and Subsidiaries | Subsequent Event | Forecast
Long-term Purchase Commitment [Line Items]
Operating lease right-of-use assets	51,300
Finance lease liabilities	$ 51,300