Long-term debt - Narrative (Details) - USD ($)	Dec. 31, 2023	Mar. 16, 2023
Debt Instrument [Line Items]
2024	$ 18,000,000
2025	109,000,000
2026	174,000,000
2027	449,000,000
2028	273,000,000
HEI Facility \| Senior notes
Debt Instrument [Line Items]
Aggregate principal amount		$ 100,000,000
Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
2024	0
2025	47,000,000
2026	145,000,000
2027	280,000,000
2028	$ 68,000,000

Face (par) amount of debt instrument at time of issuance.

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