Credit agreement and changes in debt - Narrative (Details)	Nov. 01, 2023 USD ($)	May 14, 2023 USD ($) institution extensionOption	Feb. 18, 2022 USD ($) extensionOption	Aug. 23, 2023 USD ($)	Aug. 15, 2023 USD ($)	Mar. 31, 2023 USD ($)	Mar. 16, 2023 USD ($)	Dec. 28, 2022 USD ($)	Oct. 20, 2022 USD ($)	May 14, 2021 USD ($) institution
HEI Facility
Credit agreement
Credit agreement		$ 175,000,000		$ 175,000,000	$ 175,000,000					$ 175,000,000
Credit agreement, remaining borrowing capacity		157,000,000
Amount of initial drawing					$ 2,500,000
HEI Facility | Senior Notes
Credit agreement
Aggregate principal amount							$ 100,000,000
Hawaiian Electric Facility
Credit agreement
Credit agreement		200,000,000		$ 200,000,000
Credit agreement, remaining borrowing capacity		$ 180,000,000
Hawaiian Electric Facility | Subsequent Event
Credit agreement
Repayment of credit	$ 100,000,000
Hawaiian Electric Company, Inc. and Subsidiaries | Credit Facilities
Credit agreement
Number of financial institutions | institution		9								9
Number of financial institutions with extended termination date | institution		8
Hawaiian Electric Company, Inc. and Subsidiaries | Hawaiian Electric Facility
Credit agreement
Credit agreement			$ 200,000,000							$ 200,000,000
Number of extension options | extensionOption		2	2
Extension period		1 year	1 year
Extended maximum borrowing capacity			$ 275,000,000
Hawaiian Electric, Parent | Term Loan
Credit agreement
Aggregate principal amount									$ 100,000,000
Line of credit outstanding						$ 65,000,000		$ 35,000,000
Hawaiian Electric, Parent | Term Loan | SOFR
Credit agreement
Effective interest rate						5.81%