Regulatory Capital Requirements - Capital Conservation Buffer (Details)	Mar. 31, 2018	Jan. 01, 2016
Regulatory Capital Requirements
Initial capital conservation buffer (as a percent)		0.625%
Capital conservation buffer annual increase after initial year (as a percent)	0.625%
Capital conservation buffer final level (as a percent)	2.50%

Capital conservation buffer annual increase as a percentage of risk weighted assets after year one as defined by regulations.

No definition available.

Name:	fhb_CapitalConservationBufferAnnualIncreasePercentageOfRiskWeightedAssetsAfterYearOne
Namespace Prefix:	fhb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant