Bank segment (HEI only) - Securities Sold Under Agreements to Repurchase, Including Related Collateral Received From or Pledged to Counterparties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Securities sold under agreements to repurchase
Gross amount of recognized liabilities	$ 141,000	$ 93,000
Gross amount offset in the Balance Sheet	0	0
Net amount of liabilities presented in the Balance Sheet	141,000	93,000
Financial instruments	165,000	116,000
Cash collateral pledged	$ 0	0
Fair value of collateral, percent of fair value	5.00%
Repurchase liability	$ 140,859	$ 92,618
Weighted-average interest rate as of end of the period	0.65%	0.23%
Identical securities
Securities sold under agreements to repurchase
Repurchase liability	$ 141,000	$ 93,000	$ 229,000
Average amount outstanding during the year	98,000	170,000	219,000
Maximum amount outstanding as of any month-end	$ 141,000	$ 229,000	$ 277,000
Weighted-average interest rate as of end of the period	0.65%	0.23%	1.24%
Weighted-average interest rate during the year	0.26%	1.43%	1.29%
Weighted-average remaining days to maturity as of end of the period	1 day	6 days	117 days
Government entities
Securities sold under agreements to repurchase
Net amount of liabilities presented in the Balance Sheet		$ 14,000
Financial instruments		15,000
Cash collateral pledged		0
Commercial account holders
Securities sold under agreements to repurchase
Net amount of liabilities presented in the Balance Sheet	$ 141,000	79,000
Financial instruments	165,000	101,000
Cash collateral pledged	$ 0	$ 0