Bank segment (HEI only) - Investment Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Available-for-sale
Due in one year or less	$ 15,055
Due after one year through five years	62,461
Due after five years through ten years	58,250
Due after ten years	0
Total	135,766
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies	2,482,618
Total available-for-sale securities	2,618,384
Held-to-maturity
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years	59,871
Due after ten years	0
Total	59,871
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies	462,399
Amortized cost	522,270
Available-for-sale
Due in one year or less	15,298
Due after one year through five years	63,256
Due after five years through ten years	58,141
Due after ten years	0
Total	136,695
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies	2,437,923
Total available-for-sale securities	2,574,618	$ 1,970,417
Held-to-maturity
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years	59,869
Due after ten years	0
Total	59,869
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies	450,605
Total held-to-maturity securities	510,474
Gains (losses) from sales of available-for-sale investments
Proceeds	197,354	169,157	$ 19,810
Gross gains	975	9,275	653
Gross losses	(447)	0	0
Interest income from taxable and non-taxable investment securities
Taxable	42,534	29,760	31,848
Non-taxable	930	769	1,074
Total	43,464	30,529	$ 32,922
Available-for-sale securities pledged at carrying value	416,000	353,000
Available-for-sale securities, pledged at carrying value as collateral for securities sold under agreements to repurchase	161,000	92,000
Stock in federal home loan bank at cost	10,000	8,680
FHLB Des Moines
Interest income from taxable and non-taxable investment securities
Stock in federal home loan bank at cost	$ 10,000	$ 8,700