Credit agreement and changes in debt - Narrative (Details)	May 14, 2023 USD ($) extensionOption institution	Feb. 18, 2022 USD ($) extensionOption	Dec. 08, 2023 USD ($)	Aug. 23, 2023 USD ($)	Aug. 15, 2023 USD ($)	May 14, 2021 USD ($) institution
Credit Facilities | Hawaiian Electric Company, Inc. and Subsidiaries
Credit agreement
Number of financial institutions | institution	9					9
Number of financial institutions with extended termination date | institution	8
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
Hawaiian Electric Facility
Credit agreement
Credit agreement	200,000,000
Credit agreement, remaining borrowing capacity	$ 180,000,000
Hawaiian Electric Facility | Hawaiian Electric Company, Inc. and Subsidiaries
Credit agreement
Credit agreement		$ 275,000,000		$ 200,000,000		$ 200,000,000
Number of extension options | extensionOption	2	2
Extension period	1 year	1 year
Hawaiian Electric Facility | Hawaiian Electric Company, Inc. and Subsidiaries | Letter of Credit
Credit agreement
Credit agreement			$ 75,000,000