Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 19, 2017
Document and Entity Information
Entity Registrant Name	FIRST HAWAIIAN, INC.
Entity Central Index Key	0000036377
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		139,586,282
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3