Represents the interest receivable written off by reversing interest income.

No definition available.

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Namespace Prefix:	fhb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of financing receivable on nonaccrual status with no allowance for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447

+ Details

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

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

- Definition

Amount of financing receivable on nonaccrual status.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919258-210447

+ Details

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

- Definition

The amount of interest income on impaired and nonperforming loans that is due to the change in present value attributable to the passage of time.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5278-111524

+ Details

Name:	us-gaap_LoansAndLeasesReceivableImpairedInterestIncomeRecognizedChangeInPresentValueAttributableToPassageOfTime
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

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Period Type:

Allowance for Credit Losses - Amortized Cost Basis of Loans and Leases on Nonaccrual Status (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans and Leases With No Allowance for Credit Losses	$ 2,168		$ 3,156
Nonaccrual Loans and Leases	9,108		9,082
Interest income recognized on nonaccrual loans and leases	100
Accrued interest receivables written off, Interest income reversed	400
Commercial and Industrial
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans and Leases	593		518
Commercial real estate
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans and Leases With No Allowance for Credit Losses	857
Nonaccrual Loans and Leases	937		80
Construction
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans and Leases With No Allowance for Credit Losses			1,840
Nonaccrual Loans and Leases	579		2,043
Residential
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual Loans and Leases With No Allowance for Credit Losses	1,311		1,316
Nonaccrual Loans and Leases	$ 6,999		$ 6,441