Electric utility segment - Utility projects (Details)	1 Months Ended	6 Months Ended
	Nov. 30, 2019 USD ($) MW	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Nov. 30, 2021 USD ($)	Oct. 31, 2020 generationUnit transmission_line kV	Jun. 10, 2019 USD ($)	Oct. 31, 2018 USD ($)
Public Utilities, General Disclosures [Line Items]
Operating lease right-of-use assets		$ 120,600,000	$ 122,416,000
Federal
Public Utilities, General Disclosures [Line Items]
Tax credit deferral period		25 years
State
Public Utilities, General Disclosures [Line Items]
Tax credit deferral period		10 years
ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
Future O&M expense reductions						$ 150,000,000
Future cost avoidance related to capital cost and tax costs						$ 96,000,000
Hawaiian Electric Company, Inc. and Subsidiaries
Public Utilities, General Disclosures [Line Items]
Operating lease right-of-use assets		$ 99,690,000	$ 101,470,000
Hawaiian Electric Company, Inc. and Subsidiaries | ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
ERP/EAM project service period (in years)		12 years
ERP/EAM project service, savings over 12 years							$ 246,000,000
Regulatory liability for O&M expense reductions		$ 9,600,000
Hawaiian Electric Company, Inc. and Subsidiaries | West Loch PV Project
Public Utilities, General Disclosures [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		60,100,000
Federal nonrefundable tax credits		14,700,000
State nonrefundable tax credits		14,000,000
Operating lease right-of-use assets		6,400,000
Hawaiian Electric Company, Inc. and Subsidiaries | Waena Switchyard/Synchronous Condenser Project
Public Utilities, General Disclosures [Line Items]
Number of extended transmission lines | transmission_line					2
Number of kilovolts | kV					69
Number of generating units converting to synchronous condensers | generationUnit					2
Renewable energy generation project, approved funds				$ 38,800,000
Renewable energy generation project, incurred cost		10,200,000
Hawaiian Electric | PCB Contamination
Public Utilities, General Disclosures [Line Items]
Valuation allowances and reserves		10,100,000
Hawaiian Electric | ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
Regulatory liability for O&M expense reductions		4,800,000
Hawaii Electric Light | ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
Regulatory liability for O&M expense reductions		1,900,000
Maui Electric
Public Utilities, General Disclosures [Line Items]
Additional accrued investigation and estimated cleanup costs		2,700,000
Maui Electric | ERP/EAM Implementation Project
Public Utilities, General Disclosures [Line Items]
Regulatory liability for O&M expense reductions		$ 2,900,000
Regulatory liability, amortization period		5 years