Credit agreement and changes in debt - Note Purchase Agreements (Details) - Senior Notes - USD ($)	Jun. 30, 2023	Jan. 10, 2023
Series 2023A
Debt Instrument [Line Items]
Aggregate principal amount	$ 39,000,000
Fixed coupon interest rate	6.04%
Series 2023A | Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
Aggregate principal amount		$ 90,000,000
Series 2023A | Hawaiian Electric, Parent
Debt Instrument [Line Items]
Aggregate principal amount		$ 40,000,000
Fixed coupon interest rate		6.11%
Series 2023A | Hawaii Electric Light Company, Inc
Debt Instrument [Line Items]
Aggregate principal amount		$ 25,000,000
Fixed coupon interest rate		6.25%
Series 2023A | Maui Electric
Debt Instrument [Line Items]
Aggregate principal amount		$ 25,000,000
Fixed coupon interest rate		6.25%
Series 2023B
Debt Instrument [Line Items]
Aggregate principal amount	$ 61,000,000
Fixed coupon interest rate	6.10%
Series 2023B | Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
Aggregate principal amount		$ 40,000,000
Series 2023B | Hawaiian Electric, Parent
Debt Instrument [Line Items]
Aggregate principal amount		$ 40,000,000
Fixed coupon interest rate		6.25%
Series 2023C | Hawaiian Electric Company, Inc. and Subsidiaries
Debt Instrument [Line Items]
Aggregate principal amount		$ 20,000,000
Series 2023C | Hawaiian Electric, Parent
Debt Instrument [Line Items]
Aggregate principal amount		$ 20,000,000
Fixed coupon interest rate		6.70%