Bank segment (HEI only) - Off Balance Sheet Arrangements and Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended
	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
American Savings Bank (ASB)
Guarantees
Minimum reserve ratio	1.36%
FDIC insurance assessment		$ 1,200	$ 2,500	$ 2,600
American Savings Bank (ASB) | Indemnification Agreement
Guarantees
Accrued indemnification litigation obligation		1,100
Reserve for Off-balance Sheet Activities
Guarantees
Unused commitments to extend credit		1,878,791	1,859,046
Home equity line of credit
Guarantees
Unused commitments to extend credit		1,290,854	1,242,804
Commercial and commercial real estate
Guarantees
Unused commitments to extend credit		484,806	515,058
Consumer
Guarantees
Unused commitments to extend credit		70,088	70,292
Residential 1-4 family
Guarantees
Unused commitments to extend credit		21,131	17,552
Commercial and financial standby letters of credit
Guarantees
Unused commitments to extend credit		$ 11,912	$ 13,340