Bank segment (HEI only) - Reconciliation of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Gain on sale of investment securities, net	$ 528	$ 9,275	$ 653
Total revenues	2,850,379	2,579,775	2,873,948
Total interest expense	99,403	99,808	109,339
Provision for credit losses	(26,425)	49,811	23,480
Less: Retirement defined benefits expense (credit)—other than service costs	(5,848)	3,210	2,806
Total expenses	2,464,313	2,268,282	2,525,927
Operating income	386,066	311,493	348,021
Add back: Retirement defined benefits expense (credit)—other than service costs	(5,848)	3,210	2,806
Add back: Gain on sale of investment securities, net	528	9,275	653
Income before income taxes	310,863	240,624	271,409
American Savings Bank (ASB)
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Interest and dividend income	242,266	244,663	266,554
Noninterest income	64,660	78,123	72,778
Less: Gain on sale of real estate	0	0	10,762
Gain on sale of investment securities, net	528	9,275	653
Total revenues	306,398	313,511	327,917
Total interest expense	5,040	11,114	18,440
Provision for credit losses	(25,825)	50,811	23,480
Noninterest expense	197,152	191,590	185,378
Less: Retirement defined benefits expense (credit)—other than service costs	(1,828)	1,813	(472)
Gain on sale of properties	0	0	10,762
Total expenses	178,195	251,702	217,008
Operating income	128,203	61,809	110,909
Add back: Retirement defined benefits expense (credit)—other than service costs	(1,828)	1,813	(472)
Add back: Gain on sale of investment securities, net	528	9,275	653
Income before income taxes	$ 130,559	$ 69,271	$ 112,034