Bank segment (HEI only) - Credit Risk Profile by Internally Assigned Grade for Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Credit risk profile by internally assigned grade for loans
Total financing receivables	$ 4,671,577	$ 4,743,619	$ 4,622,068
Loans, Excluding Consumer Loans
Credit risk profile by internally assigned grade for loans
Total financing receivables	1,386,207	1,619,214
Loans, Excluding Consumer Loans | Pass
Credit risk profile by internally assigned grade for loans
Total financing receivables	1,207,576	1,418,751
Loans, Excluding Consumer Loans | Special mention
Credit risk profile by internally assigned grade for loans
Total financing receivables	99,844	90,770
Loans, Excluding Consumer Loans | Substandard
Credit risk profile by internally assigned grade for loans
Total financing receivables	78,319	109,693
Loans, Excluding Consumer Loans | Doubtful
Credit risk profile by internally assigned grade for loans
Total financing receivables	468	0
Loans, Excluding Consumer Loans | Loss
Credit risk profile by internally assigned grade for loans
Total financing receivables	0	0
Commercial real estate
Credit risk profile by internally assigned grade for loans
Total financing receivables	733,106	800,395	690,561
Commercial real estate | Pass
Credit risk profile by internally assigned grade for loans
Total financing receivables	630,877	701,657
Commercial real estate | Special mention
Credit risk profile by internally assigned grade for loans
Total financing receivables	49,347	65,541
Commercial real estate | Substandard
Credit risk profile by internally assigned grade for loans
Total financing receivables	52,882	33,197
Commercial real estate | Doubtful
Credit risk profile by internally assigned grade for loans
Total financing receivables	0	0
Commercial real estate | Loss
Credit risk profile by internally assigned grade for loans
Total financing receivables	0	0
Commercial construction
Credit risk profile by internally assigned grade for loans
Total financing receivables	108,273	126,768	100,796
Commercial construction | Pass
Credit risk profile by internally assigned grade for loans
Total financing receivables	83,757	102,955
Commercial construction | Special mention
Credit risk profile by internally assigned grade for loans
Total financing receivables	22,500	0
Commercial construction | Substandard
Credit risk profile by internally assigned grade for loans
Total financing receivables	2,016	23,813
Commercial construction | Doubtful
Credit risk profile by internally assigned grade for loans
Total financing receivables	0	0
Commercial construction | Loss
Credit risk profile by internally assigned grade for loans
Total financing receivables	0	0
Commercial
Credit risk profile by internally assigned grade for loans
Total financing receivables	544,828	692,051	$ 758,659
Commercial | Pass
Credit risk profile by internally assigned grade for loans
Total financing receivables	492,942	614,139
Commercial | Special mention
Credit risk profile by internally assigned grade for loans
Total financing receivables	27,997	25,229
Commercial | Substandard
Credit risk profile by internally assigned grade for loans
Total financing receivables	23,421	52,683
Commercial | Doubtful
Credit risk profile by internally assigned grade for loans
Total financing receivables	468	0
Commercial | Loss
Credit risk profile by internally assigned grade for loans
Total financing receivables	$ 0	$ 0