Regulatory restrictions on net assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Regulatory restrictions on net assets
Common stock equity	$ 2,390,884	$ 2,337,502	$ 2,280,260	$ 2,162,280
Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory restrictions on net assets
Restrictions on transfer of net assets to the parent in the form of cash dividends, loans and advances	$ 919,000
Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory restrictions on net assets
Distribution restrictions, percent of earnings in current year and 5 preceding years if capitalization rate is less than 35%	80.00%
Total capitalization rate of HEI's electric utility subsidiaries	57.00%
Common stock equity	$ 2,261,899	2,141,918	$ 2,047,352	$ 1,957,641
American Savings Bank (ASB)
Regulatory restrictions on net assets
Common stock equity	727,818	$ 736,175
Restrictions on transfer of net assets to the parent in the form of cash dividends, loans and advances	$ 232,000