Leases - Lease Liabilities (Details)	3 Months Ended
	Mar. 31, 2019 USD ($)
Supplemental Cash Flows Information
Operating cash flows from operating leases, cash paid for amounts included in the measurement of lease liabilities	$ 1,757,000
Operating cash flows from finance leases, cash paid for amounts included in the measurement of lease liabilities	$ 28,000
Weighted Average Remaining Lease Term, Operating leases	15 years 2 months 12 days
Weighted Average Remaining Lease Term, Finance leases	3 years 2 months 12 days
Weighted Average Discount Rate, Operating leases	3.43%
Weighted Average Discount Rate, Finance leases	6.78%
Operating lease right-of-use assets	$ 48,700,000
Other assets	us-gaap:OtherAssetsMember
Finance lease right-of use assets	$ 0
Premises and equipment	fhb:PremisesAndEquipmentMember
Operating lease liabilities	$ 48,900,000
Other liabilities	us-gaap:OtherLiabilitiesMember
Finance lease liabilities	$ 0
Long-term borrowings	us-gaap:LongTermDebtMember
Right-of-use assets obtained in exchange for new operating lease obligations	$ 0
Right-of-use assets obtained in exchange for new finance lease obligations	$ 0