Bank segment (HEI only) - Available For Sale Investment Securities (Details) $ in Thousands	Dec. 31, 2023 USD ($) issue	Dec. 31, 2022 USD ($) issue
Available-for-sale
Amortized cost	$ 1,341,886
Available-for-sale investment securities	1,136,439	$ 1,429,667
Held-to-maturity
Amortized cost	1,201,314	1,251,747
Held-to-maturity investment securities	1,103,668
American Savings Bank (ASB)
Available-for-sale
Amortized cost	1,341,886	1,678,205
Gross unrealized gains	0	0
Gross unrealized losses	(205,447)	(248,538)
Available-for-sale investment securities	$ 1,136,439	$ 1,429,667
Number of issues, less than 12 months | issue	3	129
Fair value, less than 12 months	$ 1,649	$ 526,681
Gross unrealized losses, less than 12 months	$ (22)	$ (61,147)
Number of issues, more than 12 months | issue	128	75
Fair value, 12 months or longer	$ 1,120,432	$ 888,084
Gross unrealized losses, 12 months or longer	(205,425)	(187,391)
Held-to-maturity
Amortized cost	1,201,314	1,251,747
Gross unrealized gains	2,221	2,670
Gross unrealized losses	(99,867)	(103,446)
Held-to-maturity investment securities	$ 1,103,668	$ 1,150,971
Number of issues, less than 12 months | issue	37	23
Fair value, less than 12 months	$ 378,326	$ 200,503
Gross unrealized losses, less than 12 months	$ (7,610)	$ (13,815)
Number of issues, more than 12 months | issue	46	53
Fair value, 12 months or longer	$ 484,864	$ 601,792
Gross unrealized losses, 12 months or longer	(92,257)	(89,631)
American Savings Bank (ASB) | U.S. Treasury and federal agency obligations
Available-for-sale
Amortized cost	12,437	88,344
Gross unrealized gains	0	0
Gross unrealized losses	(427)	(7,281)
Available-for-sale investment securities	$ 12,010	$ 81,063
Number of issues, less than 12 months | issue	0	12
Fair value, less than 12 months	$ 0	$ 41,201
Gross unrealized losses, less than 12 months	$ 0	$ (2,120)
Number of issues, more than 12 months | issue	9	4
Fair value, 12 months or longer	$ 12,010	$ 39,862
Gross unrealized losses, 12 months or longer	(427)	(5,161)
Held-to-maturity
Amortized cost	59,917	59,894
Gross unrealized gains	0	0
Gross unrealized losses	(7,135)	(8,478)
Held-to-maturity investment securities	$ 52,782	$ 51,416
Number of issues, less than 12 months | issue	0	1
Fair value, less than 12 months	$ 0	$ 16,874
Gross unrealized losses, less than 12 months	$ 0	$ (3,222)
Number of issues, more than 12 months | issue	3	2
Fair value, 12 months or longer	$ 52,782	$ 34,542
Gross unrealized losses, 12 months or longer	(7,135)	(5,256)
American Savings Bank (ASB) | Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies
Available-for-sale
Amortized cost	1,279,852	1,530,582
Gross unrealized gains	0	0
Gross unrealized losses	(202,684)	(237,614)
Available-for-sale investment securities	$ 1,077,168	$ 1,292,968
Number of issues, less than 12 months | issue	3	113
Fair value, less than 12 months	$ 1,649	$ 455,836
Gross unrealized losses, less than 12 months	$ (22)	$ (56,999)
Number of issues, more than 12 months | issue	116	70
Fair value, 12 months or longer	$ 1,075,519	$ 837,132
Gross unrealized losses, 12 months or longer	(202,662)	(180,615)
Held-to-maturity
Amortized cost	1,141,397	1,191,853
Gross unrealized gains	2,221	2,670
Gross unrealized losses	(92,732)	(94,968)
Held-to-maturity investment securities	$ 1,050,886	$ 1,099,555
Number of issues, less than 12 months | issue	37	22
Fair value, less than 12 months	$ 378,326	$ 183,629
Gross unrealized losses, less than 12 months	$ (7,610)	$ (10,593)
Number of issues, more than 12 months | issue	43	51
Fair value, 12 months or longer	$ 432,082	$ 567,250
Gross unrealized losses, 12 months or longer	(85,122)	(84,375)
American Savings Bank (ASB) | Corporate bonds
Available-for-sale
Amortized cost	35,239	44,377
Gross unrealized gains	0	0
Gross unrealized losses	(2,336)	(3,643)
Available-for-sale investment securities	$ 32,903	$ 40,734
Number of issues, less than 12 months | issue	0	4
Fair value, less than 12 months	$ 0	$ 29,644
Gross unrealized losses, less than 12 months	$ 0	$ (2,028)
Number of issues, more than 12 months | issue	3	1
Fair value, 12 months or longer	$ 32,903	$ 11,090
Gross unrealized losses, 12 months or longer	(2,336)	(1,615)
American Savings Bank (ASB) | Mortgage revenue bonds
Available-for-sale
Amortized cost	14,358	14,902
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Available-for-sale investment securities	$ 14,358	$ 14,902
Number of issues, less than 12 months | issue	0	0
Fair value, less than 12 months	$ 0	$ 0
Gross unrealized losses, less than 12 months	$ 0	$ 0
Number of issues, more than 12 months | issue	0	0
Fair value, 12 months or longer	$ 0	$ 0
Gross unrealized losses, 12 months or longer	$ 0	$ 0