Electric utility segment - Utility Projects (Details)	1 Months Ended	12 Months Ended
	Nov. 30, 2019 USD ($) MW	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jun. 10, 2019 USD ($)	Oct. 31, 2018 USD ($)
Federal
Regulatory Projects and Legal Obligations [Line Items]
Tax credit deferral period		25 years
State
Regulatory Projects and Legal Obligations [Line Items]
Tax credit deferral period		10 years
Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
Regulatory liabilities		$ 29,760,000	$ 37,301,000
Hawaiian Electric Company, Inc. and Subsidiaries | ERP/EAM Implementation Project
Regulatory Projects and Legal Obligations [Line Items]
ERP/EAM project service period (in years)		12 years
ERP/EAM required pass-through savings					$ 246,000,000
ERP/EAM implementation project, expected future O&M expense reductions				$ 150,000,000
ERP/EAM implementation project, future cost avoidance related to capital costs and tax costs				$ 96,000,000
ERP/EAM regulatory liability for operation and maintenance expense reductions		$ 8,600,000
Hawaiian Electric Company, Inc. and Subsidiaries | West Loch PV Project
Regulatory Projects and Legal Obligations [Line Items]
Solar project, energy production (in megawatts) | MW	20
Solar project, project cap	$ 67,000,000
Solar project, project cap for in-kind work	$ 4,700,000
Solar project, cost incurred		58,800,000
Federal nonrefundable tax credits		14,700,000
State nonrefundable tax credits		$ 14,000,000
Solar project, maximum energy costs (in dollars per KWH)		9.56
Regulatory liabilities		$ 700,000
Hawaiian Electric | ERP/EAM Implementation Project
Regulatory Projects and Legal Obligations [Line Items]
ERP/EAM regulatory liability for operation and maintenance expense reductions		5,400,000
HELCO | ERP/EAM Implementation Project
Regulatory Projects and Legal Obligations [Line Items]
ERP/EAM regulatory liability for operation and maintenance expense reductions		1,300,000
Regulatory liability to be flowed through to customers			1,600,000
Maui Electric | ERP/EAM Implementation Project
Regulatory Projects and Legal Obligations [Line Items]
ERP/EAM regulatory liability for operation and maintenance expense reductions		$ 1,900,000
Regulatory liability, amortization period		5 years
Regulatory liability to be flowed through to customers			$ 2,300,000