Leases - Lease Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows paid for operating leases	$ 8,802
Operating cash flows paid for finance leases	10
Financing cash flows paid for finance leases	10	$ 10	$ 10
Right-of-use assets obtained in exchange for new lease obligations, Operating leases	$ 1,401
Weighted Average Remaining Lease Term, Operating leases (years)	15 years 8 months 12 days
Weighted Average Remaining Lease Term, Finance leases (years)	2 years 6 months
Weighted Average Discount Rate, Operating leases	3.36%
Weighted Average Discount Rate, Finance leases	6.78%
Operating lease right-of-use assets	$ 44,300
Other assets	us-gaap:OtherAssetsMember
Finance lease right-of use assets	$ 0
Premises and equipment	fhb:PremisesAndEquipmentMember
Operating lease liabilities	$ 44,400
Other liabilities	us-gaap:OtherLiabilitiesMember
Finance lease liabilities	$ 19	$ 26
Long-term borrowings	us-gaap:LongTermDebtMember