Organization and Basis of Presentation (Details)	Sep. 30, 2024
First Hawaiian, Inc. (FHI)
Capitalization
Outstanding common stock owned (as a percent)	100.00%

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.

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