Bank segment (HEI only) - Investment Securities (Details)		12 Months Ended
	Jun. 01, 2015 bank	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Amortized Cost
Due in one year or less		$ 9,979,000
Due after one year through five years		77,179,000
Due after five years through ten years		81,411,000
Due after ten years		40,373,000
Total amortized cost		208,942,000
Mortgage-related securities-FNMA, FHLMC and GNMA - amortized cost		909,408,000
Total available-for-sale securities, amortized cost		1,118,350,000	$ 823,756,000
Fair value
Due in one year or less		10,001,000
Due after one year through five years		77,126,000
Due after five years through ten years		81,083,000
Due after ten years		39,498,000
Total fair value		207,708,000
Mortgage-related securities-FNMA, FHLMC and GNMA - fair value		897,474,000
Estimated fair value		1,105,182,000	820,648,000
Gains (losses) from sales of available-for-sale investments
Proceeds		16,423,000	0	$ 79,564,000
Available-for-sale securities pledged at carrying value		277,100,000	100,500,000
Available-for-sale securities, pledged at carrying value as collateral for securities sold under agreements to repurchase		114,900,000	260,500,000
Interest income from taxable and non-taxable investment securities
Taxable		19,166,000	15,120,000	11,666,000
Non-taxable		18,000	0	279,000
Total		19,184,000	15,120,000	11,945,000
Number of banks merging | bank	2
Redemption of stock from Federal Home Loan Bank		7,233,000	60,223,000	23,244,000
FHLB Seattle
Interest income from taxable and non-taxable investment securities
Cost method investments		11,200,000	10,700,000
Redemption of stock from Federal Home Loan Bank		0	58,600,000
Mortgage-related securities - FNMA, FHLMC and GNMA
Gains (losses) from sales of available-for-sale investments
Proceeds		16,400,000	0	79,600,000
Gross gains		600,000	0	2,800,000
Gross losses		$ 0	$ 0	$ 0