Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 03, 2020
Cover page.
Entity Registrant Name	PREMIER FINANCIAL BANCORP, INC.
Entity Central Index Key	0000887919
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		14,673,257
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	000-20908
Entity Tax Identification Number	61-1206757
Entity Incorporation, State or Country Code	KY
Entity Address, Address Line One	2883 Fifth Avenue
Entity Address, City or Town	Huntington
Entity Address, State or Province	WV
Entity Address, Postal Zip Code	25702
City Area Code	304
Local Phone Number	525-1600
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	PFBI
Security Exchange Name	NASDAQ