Shareholders' equity - Accumulated other comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 2,202,499	$ 2,390,884
Current period other comprehensive income (loss)	20,488	(117,159)
Ending balance	2,237,955	2,303,642
AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(336,028)	(52,533)
Current period other comprehensive income (loss)	20,488	(117,159)
Ending balance	(315,540)	(169,692)
Net unrealized gains (losses) on securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(328,904)	(32,037)
Current period other comprehensive income (loss)	20,282	(120,407)
Ending balance	(308,622)	(152,444)
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1,991	(3,638)
Current period other comprehensive income (loss)	138	3,072
Ending balance	2,129	(566)
Retirement benefit plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(9,115)	(16,858)
Current period other comprehensive income (loss)	68	176
Ending balance	(9,047)	(16,682)
Hawaiian Electric Company, Inc. and Subsidiaries
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	2,344,170	2,261,899
Current period other comprehensive income (loss)	(45)	51
Ending balance	2,358,884	2,276,884
Hawaiian Electric Company, Inc. and Subsidiaries | AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	2,861	(3,280)
Current period other comprehensive income (loss)	(45)	51
Ending balance	2,816	(3,229)
Hawaiian Electric Company, Inc. and Subsidiaries | Retirement benefit plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	2,861	(3,280)
Current period other comprehensive income (loss)	(45)	51
Ending balance	$ 2,816	$ (3,229)