Electric utility segment - Annual decoupling filings summary (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
Regulatory Projects and Legal Obligations [Line Items]
Incremental Performance Incentive Mechanisms (net)	$ (0.2)
Incremental EPRM/MPIR Revenue Adjustment	4.9
Other	0.5
Net incremental amount to be collected under the RBA rate tariffs	5.1
Hawaiian Electric, Parent
Regulatory Projects and Legal Obligations [Line Items]
Incremental Performance Incentive Mechanisms (net)	(0.4)
Incremental EPRM/MPIR Revenue Adjustment	2.5
Other	0.4
Net incremental amount to be collected under the RBA rate tariffs	2.5
Hawaii Electric Light
Regulatory Projects and Legal Obligations [Line Items]
Incremental Performance Incentive Mechanisms (net)	0.1
Incremental EPRM/MPIR Revenue Adjustment	1.4
Other	0.1
Net incremental amount to be collected under the RBA rate tariffs	1.5
Maui Electric
Regulatory Projects and Legal Obligations [Line Items]
Incremental Performance Incentive Mechanisms (net)	0.1
Incremental EPRM/MPIR Revenue Adjustment	1.0
Other	0.0
Net incremental amount to be collected under the RBA rate tariffs	$ 1.1