Electric utility segment - Regulatory Proceedings (Details) $ in Thousands			3 Months Ended	12 Months Ended
	Dec. 29, 2023 USD ($)	Dec. 23, 2020 USD ($)	Mar. 31, 2024 USD ($) MWh project agreement	Dec. 31, 2023 USD ($)	Dec. 31, 2019 USD ($) agreement	Mar. 11, 2024 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Jun. 17, 2022 mechanism	Jun. 10, 2019 USD ($)	Oct. 31, 2018 USD ($)
Regulatory Projects and Legal Obligations [Line Items]
PUC proposal period (in days)		45 days
Public utilities, modified pilot process proposal period (in days)			15 days
Propose pilots annual cap			$ 10,000
Performance incentive mechanism, accrued award							$ 10
Potential total annual maximum reward			$ 2,000
Advanced metering infrastructure term (in years)			3 years
Regulatory assets			$ 315,067	$ 294,804
Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
Number of performance incentive mechanisms | mechanism									2
Multi-year rate period (in years)		5 years
Customer dividend, negative adjustment percentage		0.22%
Savings commitment liability, annual rate		$ 6,600
Earnings sharing mechanism, actual return on equity, dead band percentage above or below target			3.00%
Approved return on equity, percentage			9.50%
Percentage sharing between customers and utilities			0.50
Earnings sharing mechanism, actual earning, above or below dead band			1.50%
Percentage sharing for any further difference			0.90
MPIR and EPRM requested amount			$ 33,100
EPRM approved projects | project			4
EPRM approved projects, capital costs			$ 218,500
Number of projects | project			3
Estimated capital costs			$ 215,900
2022 deferred cost recovery approved						$ 3,000
Decoupling order, service reliability performance, historical measurement period (in years)			10 years
Maximum penalty, percent of ROE			0.20%
Service reliability, pending adjusted maximum penalty amount			$ 6,400
Service reliability, estimated penalties				3,700
Dead band percentage above or below the target			3.00%
Call center performance, maximum penalty percentage			0.08%
Call center performance, pending adjusted maximum penalty			$ 1,400
Number of power purchase agreements (PPAs) (in agreements) | agreement					7
Number of incentive earned power purchase agreements | agreement			2
Incentives accrued			$ 100		$ 1,700			$ 100
Interpolated RPS rate goal, year one and two (in dollars per MWh) | MWh			20
Interpolated RPS rate goal, year three (in dollars per MWh) | MWh			15
Interpolated RPS rate goal, after year three (in dollars per MWh) | MWh			10
Failure to meet RPS targets, penalty rate (in dollars per MWh) | MWh			20
Accrued estimated rewards				400
Potential total annual maximum reward			$ 1,500
Public utilities, grid services procurement performance incentive mechanism, accrued estimated rewards				1,100
Potential total annual maximum reward			3,000
Total annual maximum penalty			900
Interconnection approval PIM, accrued estimated rewards				3,000
Performance incentive mechanism, maximum reward			$ 2,000
Performance incentive mechanism, term (in years)			3 years
Target performance historical measurement period (in years)			10 years
Percent of return on equity			0.03%
Pending adjusted amount			$ 1,000
Target performance period (in months)			10 months
Target deadband period (in months)			2 months
Accrued earned rewards, net of penalties				900
Recovery of deferral costs period (in years)	3 years
Hawaiian Electric Company, Inc. and Subsidiaries | Honolulu Generating Units 8 and 9
Regulatory Projects and Legal Obligations [Line Items]
Regulatory asset amortization period			9 years
Regulatory assets			$ 29,100
Hawaiian Electric Company, Inc. and Subsidiaries | Suspension Of Disconnections
Regulatory Projects and Legal Obligations [Line Items]
Regulatory assets			1,000
Hawaiian Electric Company, Inc. and Subsidiaries | Natural Disasters and Other Casualty Events
Regulatory Projects and Legal Obligations [Line Items]
Regulatory assets			22,600
Hawaiian Electric Company, Inc. and Subsidiaries | COVID-19
Regulatory Projects and Legal Obligations [Line Items]
Public utilities in regulatory assets	$ 8,800
Regulatory assets			$ 8,600
Hawaiian Electric, Parent
Regulatory Projects and Legal Obligations [Line Items]
Public utilities retained percentage			20.00%
Accrued earned rewards, net of penalties				1,200
Hawaii Electric Light Company, Inc
Regulatory Projects and Legal Obligations [Line Items]
Accrued earned rewards, net of penalties				(600)
Maui Electric
Regulatory Projects and Legal Obligations [Line Items]
Accrued earned rewards, net of penalties				$ 300
Schofield Generation Station | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
MPIR requested amount			$ 16,500
West Loch PV Project | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
MPIR requested amount			3,300
Grid Modernization Strategy Phase 1 Project | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
MPIR requested amount			11,200
Waiawa UFLS Project | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
EPRM requested amount			$ 100
ERP/EAM Implementation Project | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
ERP/EAM project service period (in years)			12 years
ERP/EAM project service, savings over 12 years											$ 246,000
Future O&M expense reductions										$ 150,000
Future cost avoidance related to capital cost and tax costs										$ 96,000
Regulatory liability, amortization period (in years)			5 years
Regulatory liability for O&M expense reductions			$ 12,900
ERP/EAM Implementation Project | Hawaiian Electric, Parent
Regulatory Projects and Legal Obligations [Line Items]
Regulatory liability for O&M expense reductions			2,200
ERP/EAM Implementation Project | Hawaii Electric Light Company, Inc
Regulatory Projects and Legal Obligations [Line Items]
Regulatory liability for O&M expense reductions			4,300
ERP/EAM Implementation Project | Maui Electric
Regulatory Projects and Legal Obligations [Line Items]
Regulatory liability for O&M expense reductions			6,400
Waena Switchyard/Synchronous Project | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
EPRM requested amount			$ 2,000