Bank segment (HEI only) - Investment Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 16,974
Due after one year through five years	41,551
Due after five years through ten years	31,511
Due after ten years	27,185
Amortized cost, available-for-sale securities with a single maturity date	117,221
Mortgage-related securities-FNMA, FHLMC and GNMA - amortized cost	1,825,893
Total amortized cost	1,943,114
Mortgage-related securities-FNMA, FHLMC and GNMA, amortized cost basis	226,947
Debt Securities, Held-to-maturity	226,947	$ 139,451
Fair value
Due in one year or less	17,098
Due after one year through five years	43,285
Due after five years through ten years	33,290
Due after ten years	27,185
Available-for-sale securities with a single maturity date	120,858
Mortgage-related securities-FNMA, FHLMC and GNMA - fair value	1,849,559
Total fair value	1,970,417	1,232,826
Mortgage-related securities - FNMA, FHLMC and GNMA, Fair Value	229,963
Held-to-maturity securities, Fair Value	229,963	143,467
Gains (losses) from sales of available-for-sale investments
Proceeds	169,157	19,810	$ 0
Gross gains	9,275	653	0
Gross losses	0	0	0
Interest income from taxable and non-taxable investment securities
Taxable	29,760	31,848	37,153
Non-taxable	769	1,074	609
Total	30,529	32,922	$ 37,762
Available-for-sale securities pledged at carrying value	445,000	546,000
Available-for-sale securities, pledged at carrying value as collateral for securities sold under agreements to repurchase	92,000	130,000
Stock in federal home loan bank at cost	8,680	8,434
FHLB Des Moines
Interest income from taxable and non-taxable investment securities
Stock in federal home loan bank at cost	$ 8,700	$ 8,400