Bank segment (HEI only) - Investment Securities (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2022 USD ($) security	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Available-for-sale
Due in one year or less		$ 1,419
Due after one year through five years		46,257
Due after five years through ten years		14,358
Due after ten years		0
Total		62,034
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies		1,279,852
Amortized cost		1,341,886
Held-to-maturity
Due in one year or less		0
Due after one year through five years		39,832
Due after five years through ten years		20,085
Due after ten years		0
Total		59,917
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies		1,141,397
Amortized cost		1,201,314	$ 1,251,747
Available-for-sale
Due in one year or less		1,404
Due after one year through five years		43,509
Due after five years through ten years		14,358
Due after ten years		0
Total		59,271
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies		1,077,168
Total available-for-sale securities		1,136,439	1,429,667
Held-to-maturity
Due in one year or less		0
Due after one year through five years		35,597
Due after five years through ten years		17,185
Due after ten years		0
Total		52,782
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies		1,050,886
Total held-to-maturity securities		1,103,668
Gains (losses) from sales of available-for-sale investments
Proceeds		170,481	0	$ 197,354
Gross gains		0	0	975
Gross losses		(14,965)	0	(447)
Tax expense (benefit) on realized gains (losses)		(4,011)	0	142
Interest income from taxable and non-taxable investment securities
Taxable		56,450	56,731	42,534
Non-taxable		1,645	1,313	930
Total		58,095	58,044	$ 43,464
Available-for-sale securities pledged at carrying value		1,700,000	900,000
Available-for-sale securities, pledged at carrying value as collateral for securities sold under agreements to repurchase		0	327,000
Stock in federal home loan bank at cost		14,728	26,560
American Savings Bank (ASB)
Available-for-sale
Amortized cost		1,341,886	1,678,205
Held-to-maturity
Amortized cost		1,201,314	1,251,747
Available-for-sale
Total available-for-sale securities		1,136,439	1,429,667
Held-to-maturity
Total held-to-maturity securities		1,103,668	1,150,971
Interest income from taxable and non-taxable investment securities
Number of available-for-sale investment securities transferred | security	66
Available-for-sale and held-to-maturity, fair value	$ 755,000
Gross realized losses on available-for-sale securities	$ 206,000
Stock in federal home loan bank at cost		14,728	26,560
Unamortized debt amount		133,000
FHLB Des Moines
Interest income from taxable and non-taxable investment securities
Stock in federal home loan bank at cost		$ 14,700	$ 26,600