Bank segment (HEI only) - Loan Modifications (Details)	12 Months Ended
	Dec. 31, 2019 USD ($) contract	Dec. 31, 2018 USD ($) contract	Dec. 31, 2017 USD ($) contract
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	25	70	57
Pre-modification outstanding recorded investment	$ 8,821,000	$ 10,728,000	$ 3,935,000
Post-modification outstanding recorded investment	$ 680,000	$ 815,000	$ 889,000
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	2	1
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 327,000	$ 222,000
Commitments to borrowers whose loan terms are impaired or modified under troubled debt restructuring	0	0
Consumer mortgage loans collateralized by residential real estate property in foreclosure process	$ 3,500,000	$ 4,200,000
Residential 1-4 family
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	11	3	3
Pre-modification outstanding recorded investment	$ 1,770,000	$ 566,000	$ 469,000
Post-modification outstanding recorded investment	$ 190,000	$ 26,000	$ 65,000
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	0	1
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 0	$ 222,000
Commercial real estate
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	0	0	0
Pre-modification outstanding recorded investment	$ 0	$ 0	$ 0
Post-modification outstanding recorded investment	$ 0	$ 0	$ 0
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	0	0
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 0	$ 0
Home equity line of credit
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	3	53	44
Pre-modification outstanding recorded investment	$ 442,000	$ 6,659,000	$ 2,791,000
Post-modification outstanding recorded investment	$ 73,000	$ 578,000	$ 545,000
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	1	0
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 81,000	$ 0
Residential land
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	3	2	1
Pre-modification outstanding recorded investment	$ 1,086,000	$ 1,338,000	$ 92,000
Post-modification outstanding recorded investment	$ 0	$ 0	$ 0
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	0	0
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 0	$ 0
Commercial construction
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	0	0	0
Pre-modification outstanding recorded investment	$ 0	$ 0	$ 0
Post-modification outstanding recorded investment	$ 0	$ 0	$ 0
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	0	0
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 0	$ 0
Residential construction
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	0	0	0
Pre-modification outstanding recorded investment	$ 0	$ 0	$ 0
Post-modification outstanding recorded investment	$ 0	$ 0	$ 0
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	0	0
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 0	$ 0
Commercial
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	8	12	8
Pre-modification outstanding recorded investment	$ 5,523,000	$ 2,165,000	$ 525,000
Post-modification outstanding recorded investment	$ 417,000	$ 211,000	$ 250,000
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	1	0
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 246,000	$ 0
Consumer
Loan modifications determined to be troubled debt restructurings
Number of contracts | contract	0	0	1
Pre-modification outstanding recorded investment	$ 0	$ 0	$ 58,000
Post-modification outstanding recorded investment	$ 0	$ 0	$ 29,000
Troubled debt restructuring that subsequently defaulted, number of contracts | contract	0	0	0
Troubled debt restructuring that subsequently defaulted, recorded investment	$ 0	$ 0	$ 0
Troubled debt restructurings real estate loans
Loan modifications determined to be troubled debt restructurings
Minimum period of payment default of loans determined to be TDRs	90 days	90 days	90 days