Electric utility segment - Regulatory proceedings (Details) $ in Millions				3 Months Ended	6 Months Ended	12 Months Ended
	Nov. 12, 2021	Feb. 16, 2021 agreement	Dec. 23, 2020 USD ($)	Nov. 30, 2021 agreement	Jun. 30, 2022 USD ($) MWh contract project	Dec. 31, 2021 USD ($)	Dec. 31, 2019 USD ($) agreement	Jun. 17, 2022 mechanism staff	Feb. 28, 2022 USD ($)	Jun. 01, 2021 mechanism	Mar. 23, 2021 mechanism	Dec. 31, 2020 agreement	Jul. 09, 2020 agreement
Regulatory Projects and Legal Obligations [Line Items]
Propose pilots annual cap			$ 10.0
Potential total annual maximum reward					$ 2.0
Advanced metering infrastructure term					3 years
Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
Number of performance incentive mechanisms of concern | mechanism								11
Number of staff proposing penalty-only PIMs | staff								7
Number of performance incentive mechanisms | mechanism								2		3	2
Number of performance incentive mechanisms, penalty-only | mechanism								1
Multi-year rate period			5 years
Customer dividend, negative adjustment percentage			0.22%
Savings commitment liability, annual rate			$ 6.6
Earnings sharing mechanism, actual return on equity, dead band percentage above or below target					3.00%
Approved return on equity, percentage					9.50%
Earnings sharing mechanism, actual earning, above or below dead band					1.50%
MPIR requested amount					$ 25.9
EPRM approved projects | contract					2
EPRM approved projects, capital costs					$ 41.0
Number of projects | project					5
Estimated capital costs					$ 450.0
Development period	3 years
2021 deferred costs to be reviewed by the PUC									$ 0.1
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					$ 6.8
Service reliability, estimated penalties					$ 0.2
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					$ 1.4
Number of power purchase agreements (PPAs) (in agreements) | agreement		1					7
Incentives accrued						$ 0.1	$ 1.7
Number of grid service purchase agreements | agreement												2	2
Number of PPAs approved | agreement				2
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
Estimated rewards						1.0
Potential total annual maximum reward					$ 1.5
Potential total annual maximum reward					3.0
Total annual maximum penalty					0.9
Interconnection approval PIM, accrued estimated rewards						2.8
Performance incentive mechanism, maximum reward					$ 2.0
Performance incentive mechanism, term					3 years
Target performance historical measurement period					10 years
Percent of return on equity					300.00%
Pending adjusted amount					$ 1.0
Target performance period					10 months
Target deadband period					2 months
Accrued estimated rewards, net of penalties						3.7
Hawaiian Electric
Regulatory Projects and Legal Obligations [Line Items]
Public utilities retained percentage					20.00%
Public utilities retained amount					$ 5.0
Accrued estimated rewards, net of penalties						2.8
Hawaii Electric Light
Regulatory Projects and Legal Obligations [Line Items]
Public utilities retained percentage					5.00%
Public utilities retained amount					$ 1.0
Accrued estimated rewards, net of penalties						0.4
Maui Electric
Regulatory Projects and Legal Obligations [Line Items]
Public utilities retained percentage					5.00%
Public utilities retained amount					$ 1.0
Accrued estimated rewards, net of penalties						$ 0.5
Schofield Generation Station | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
MPIR requested amount					16.5
West Loch PV Project | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
MPIR requested amount					3.3
Grid Modernization Strategy Phase 1 Project | Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory Projects and Legal Obligations [Line Items]
MPIR requested amount					$ 6.1