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

Percentage of securities comprised of collateralized loan obligations rated AA or better and obligations issued by local state and political subdivisions rated AA or better.

No definition available.

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

Amount of increase (decrease) in allowance for credit loss of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Name:	us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLossPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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.

No definition available.