Summary of significant accounting policies - General, Cash, and PPE (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) branch	Dec. 31, 2021 USD ($)	Dec. 31, 2020
Significant Accounting Policies [Line Items]
Number of branches	38
Restricted cash | $	$ 5,100	$ 5,900
Oahu
Significant Accounting Policies [Line Items]
Number of branches	27
Maui
Significant Accounting Policies [Line Items]
Number of branches	5
Hawaii
Significant Accounting Policies [Line Items]
Number of branches	3
Kauai
Significant Accounting Policies [Line Items]
Number of branches	2
Molokai
Significant Accounting Policies [Line Items]
Number of branches	1
Hawaiian Electric Company, Inc. and Subsidiaries
Significant Accounting Policies [Line Items]
Composite annual depreciation rate	3.20%	3.20%	3.20%
Minimum
Significant Accounting Policies [Line Items]
Estimated useful life under production plant (in years)	16 years
Estimated useful life under transmission and distribution plant (in years)	10 years
Estimated useful life under general plant (in years)	5 years
Maximum
Significant Accounting Policies [Line Items]
Estimated useful life under production plant (in years)	51 years
Estimated useful life under transmission and distribution plant (in years)	79 years
Estimated useful life under general plant (in years)	50 years
Hawaiian Electric Company, Inc. and Subsidiaries
Significant Accounting Policies [Line Items]
Restricted cash | $	$ 0	$ 3,089