Represents the percentage of a loan sold with no recourse to not be subject to grading for credit quality.

No definition available.

Name:	fhb_FinancingReceivableCreditQualityNotSubjectToGradingPercentageOfLoanSoldWithNoRecourse
Namespace Prefix:	fhb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of risk factors in internal rating system for credit quality of financing receivables.

+ References

No definition available.

+ Details

Name:	fhb_FinancingReceivableInternalRatingSystemNumberOfRiskFactors
Namespace Prefix:	fhb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524

+ Details

Name:	us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_InternalInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_DoubtfulMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_UnlikelyToBeCollectedFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=fhb_CommercialAndIndustrialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=fhb_ConstructionPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_FinanceLeasesPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Allowance for Loan and Lease Losses - Credit Risk Profiles by Internally Assigned Grade (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) factor	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Credit quality
Percentage of loans sold with no recourse not subject to grading	100.00%
Number of risk factors in internal loan rating system \| factor	8
Loans and leases	$ 13,211,650	$ 13,076,191	$ 12,277,369
Loans graded
Credit quality
Loans and leases	6,928,919	6,974,069
Pass
Credit quality
Loans and leases	6,631,021	6,718,416
Special mention
Credit quality
Loans and leases	198,845	149,733
Substandard
Credit quality
Loans and leases	99,053	105,728
Doubtful
Credit quality
Loans and leases		192
Loss
Credit quality
Loans and leases	0	0
Commercial and Industrial
Credit quality
Loans and leases	2,743,242	3,208,760	3,135,266
Commercial and Industrial \| Loans graded
Credit quality
Loans and leases	2,743,242	3,208,760
Commercial and Industrial \| Pass
Credit quality
Loans and leases	2,585,908	3,069,546
Commercial and Industrial \| Special mention
Credit quality
Loans and leases	91,365	57,012
Commercial and Industrial \| Substandard
Credit quality
Loans and leases	65,969	82,010
Commercial and Industrial \| Doubtful
Credit quality
Loans and leases		192
Commercial real estate
Credit quality
Loans and leases	3,463,953	2,990,783	2,667,597
Commercial real estate \| Loans graded
Credit quality
Loans and leases	3,463,953	2,990,783
Commercial real estate \| Pass
Credit quality
Loans and leases	3,327,659	2,876,907
Commercial real estate \| Special mention
Credit quality
Loans and leases	106,331	91,298
Commercial real estate \| Substandard
Credit quality
Loans and leases	29,963	22,578
Construction
Credit quality
Loans and leases	519,241	626,757	632,911
Construction \| Loans graded
Credit quality
Loans and leases	519,241	626,757
Construction \| Pass
Credit quality
Loans and leases	515,993	625,607
Construction \| Special mention
Credit quality
Loans and leases	127	200
Construction \| Substandard
Credit quality
Loans and leases	3,121	950
Lease financing
Credit quality
Loans and leases	202,483	147,769	$ 165,066
Lease financing \| Loans graded
Credit quality
Loans and leases	202,483	147,769
Lease financing \| Pass
Credit quality
Loans and leases	201,461	146,356
Lease financing \| Special mention
Credit quality
Loans and leases	$ 1,022	1,223
Lease financing \| Substandard
Credit quality
Loans and leases		$ 190