Leases - Lease Liabilities (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Supplemental Cash Flows Information
Operating cash flows from operating leases, cash paid for amounts included in the measurement of lease liabilities	$ 3,426,000
Operating cash flows from finance leases, cash paid for amounts included in the measurement of lease liabilities	$ 61,000
Weighted Average Remaining Lease Term, Operating leases	15 years 2 months 12 days
Weighted Average Remaining Lease Term, Finance leases	3 years
Weighted Average Discount Rate, Operating leases	3.42%
Weighted Average Discount Rate, Finance leases	6.78%
Operating lease right-of-use assets	$ 47,400,000
Other assets	us-gaap:OtherAssetsMember
Finance lease right-of use assets	$ 0
Premises and equipment	fhb:PremisesAndEquipmentMember
Operating lease liabilities	$ 48,300,000
Other liabilities	us-gaap:OtherLiabilitiesMember
Finance lease liabilities	$ 28,000	$ 26,000
Long-term borrowings	us-gaap:LongTermDebtMember
Right-of-use assets obtained in exchange for new operating lease obligations	$ 680,000