Percentage of assumed growth in a stock's market price, used as an input to measure fair value.

No definition available.

Name:	fhb_FairValueInputsStockMarketPriceGrowthRate
Namespace Prefix:	fhb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value portion of asset recognized for present right to economic benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

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

- Definition

Value of input used to measure debt instrument, including, but not limited to, convertible and non-convertible debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_DebtInstrumentMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Indicates valuation technique for measuring derivative liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_DerivativeLiabilityValuationTechniqueExtensibleList
Namespace Prefix:	us-gaap_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
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

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 103
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-103

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

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

- Definition

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

+ Details

Name:	us-gaap_FinancialLiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Indicates valuation technique for measuring servicing asset.

+ References

+ Details

Name:	us-gaap_ServicingAssetValuationTechniqueExtensibleList
Namespace Prefix:	us-gaap_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
Period Type:	instant

Fair Value - Significant Unobservable Inputs Used in Fair Value Measurements (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($) M	Mar. 31, 2024 USD ($)
Fair Value, Inputs, Level 3 [Member] \| Expected Term (in months) \| Weighted Average [Member]
Fair value
Measurement input	6
Fair Value, Inputs, Level 3 [Member] \| Collateral-dependent loans
Fair value
Servicing Asset, Valuation Technique [Extensible Enumeration]	us-gaap:CostApproachValuationTechniqueMember
Fair Value, Inputs, Level 3 [Member] \| Collateral-dependent loans \| Financial Statement Values
Fair value
Assets, Fair value			$ 14,441,000
Fair Value, Inputs, Level 3 [Member] \| Collateral-dependent loans \| Financial Statement Values \| Minimum [Member]
Fair value
Measurement input			0
Fair Value, Inputs, Level 3 [Member] \| Collateral-dependent loans \| Financial Statement Values \| Maximum [Member]
Fair value
Measurement input			0.50
Fair Value, Inputs, Level 3 [Member] \| Collateral-dependent loans \| Appraisal Value
Fair value
Assets, Fair value			$ 2,560,000
Fair Value, Inputs, Level 3 [Member] \| Collateral-dependent loans \| Measurement Input, Discount Rate [Member] \| Appraisal Value \| Minimum [Member]
Fair value
Measurement input	7
Fair Value, Inputs, Level 3 [Member] \| Collateral-dependent loans \| Measurement Input, Discount Rate [Member] \| Appraisal Value \| Maximum [Member]
Fair value
Measurement input	8
Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member]
Fair value
Derivative Liability, Valuation Technique [Extensible Enumeration]	Discounted Cash Flow	Discounted Cash Flow
Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Discounted Cash Flow
Fair value
Liabilities, Fair value	$ (2,300,000)	$ (2,300,000)
Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Measurement Input, Conversion Price [Member] \| Discounted Cash Flow \| Weighted Average [Member]
Fair value
Measurement input		0.015875
Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Measurement Input, Conversion Price [Member] \| Discounted Cash Flow \| Minimum [Member]
Fair value
Measurement input	0.015289	0.015289
Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Measurement Input, Conversion Price [Member] \| Discounted Cash Flow \| Maximum [Member]
Fair value
Measurement input	0.015875	0.015875
Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Measurement Input, Long-Term Revenue Growth Rate [Member] \| Discounted Cash Flow \| Weighted Average [Member]
Fair value
Growth Rate (as a percent)	14.00%	10.00%
Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Measurement Input, Long-Term Revenue Growth Rate [Member] \| Discounted Cash Flow \| Minimum [Member]
Fair value
Growth Rate (as a percent)	(2.00%)	(6.00%)
Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Measurement Input, Long-Term Revenue Growth Rate [Member] \| Discounted Cash Flow \| Maximum [Member]
Fair value
Growth Rate (as a percent)	21.00%	25.00%
Fair Value, Nonrecurring [Member]
Fair value
Assets, Fair value		$ 0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Collateral-dependent loans
Fair value
Assets, Fair value	$ 17,001,000
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Measurement Input, Conversion Price [Member] \| Discounted Cash Flow \| Weighted Average [Member]
Fair value
Measurement input	0.015875
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Expected Term (in months) \| Discounted Cash Flow \| Weighted Average [Member]
Fair value
Measurement input \| M		5