Leases - Lease Liabilities (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Supplemental Cash Flows Information
Operating cash flows from operating leases, cash paid for amounts included in the measurement of lease liabilities	$ 7,166,000
Operating cash flows from finance leases, cash paid for amounts included in the measurement of lease liabilities	89,000
Financing cash flows from finance leases, cash paid for amounts included in the measurement of lease liabilities	$ 10,000	$ 10,000
Weighted Average Remaining Lease Term, Operating leases (years)	15 years 7 months 6 days
Weighted Average Remaining Lease Term, Finance leases (years)	2 years 9 months 18 days
Weighted Average Discount Rate, Operating leases	3.34%
Weighted Average Discount Rate, Finance leases	6.78%
Operating lease right-of-use assets	$ 46,100,000
Other assets	us-gaap:OtherAssetsMember
Finance lease right-of use assets	$ 0
Premises and equipment	fhb:PremisesAndEquipmentMember
Operating lease liabilities	$ 45,600,000
Other liabilities	us-gaap:OtherLiabilitiesMember
Finance lease liabilities	$ 18,000		$ 26,000
Long-term borrowings	us-gaap:LongTermDebtMember
Right-of-use assets obtained in exchange for new operating lease obligations	$ 1,401,000