Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Restricted Shares	Common Shares	Common Shares Premier Financial Bancorp, Inc.	Common Shares Restricted Shares	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Treasury Stock Restricted Shares
Balance, December 31, 2020 at Dec. 31, 2019	$ 594,393		$ 420,876			$ 187,149	$ (1,425)	$ (12,207)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	14,194					14,194
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	4,367						4,367
Cash dividends declared	(20,622)					(20,622)
Reissuance of treasury stock for common share awards		$ 0			$ (2,583)				$ 2,583
Reissuance of treasury stock for deferred compensation plan for Boards of Directors	59							59
Repurchase of treasury stock in connection with employee incentive program and compensation plan for Boards of Directors	(1,052)							(1,052)
Treasury Stock, Value, Acquired, Cost Method								(25,000)
Common shares issued under dividend reinvestment plan	463		463
Share-based Payment Arrangement, Noncash Expense	325		9					316
Stock Issued During Period, Value, Employee Stock Purchase Plan	310		(40)					350
Share-based Compensation	2,949		2,949
Balance, September 30, 2021 at Sep. 30, 2020	566,856		421,715			177,012	2,942	(34,813)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Conversion of Units	179		41					138
Balance, December 31, 2020 at Jun. 30, 2020	569,177		421,236			173,572	4,634	(30,265)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	10,210					10,210
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1,692)						(1,692)
Cash dividends declared	(6,770)					(6,770)
Reissuance of treasury stock for common share awards		0			(321)				321
Repurchase of treasury stock in connection with employee incentive program and compensation plan for Boards of Directors	(66)							(66)
Treasury Stock, Value, Acquired, Cost Method								(5,000)
Common shares issued under dividend reinvestment plan	220		220
Share-based Payment Arrangement, Noncash Expense	52		(11)					63
Stock Issued During Period, Value, Employee Stock Purchase Plan	111		(23)					134
Share-based Compensation	614		614
Balance, September 30, 2021 at Sep. 30, 2020	566,856		421,715			177,012	2,942	(34,813)
Balance, December 31, 2020 at Dec. 31, 2020	575,673		422,536			190,691	1,336	(38,890)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	19,808					19,808
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(7,224)						(7,224)
Cash dividends declared	(20,991)					(20,991)
Reissuance of treasury stock for common share awards		0			(2,223)				2,223
Reissuance of treasury stock for deferred compensation plan for Boards of Directors	74							74
Repurchase of treasury stock in connection with employee incentive program and compensation plan for Boards of Directors	(1,076)							(1,076)
Common shares issued under dividend reinvestment plan	655		655
Share-based Payment Arrangement, Noncash Expense	309		81					228
Stock Issued During Period, Value, Employee Stock Purchase Plan	373		98					275
Share-based Compensation	2,382		2,382
Balance, September 30, 2021 at Sep. 30, 2021	831,882		685,428			189,508	(5,888)	(37,166)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Acquisitions	261,899			$ 261,899
Balance, December 31, 2020 at Jun. 30, 2021	585,505		422,652			202,359	(2,222)	(37,284)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(5,758)					(5,758)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(3,666)						(3,666)
Cash dividends declared	(7,093)					(7,093)
Reissuance of treasury stock for common share awards		$ 0			$ (51)				$ 51
Reissuance of treasury stock for deferred compensation plan for Boards of Directors	(78)							(78)
Common shares issued under dividend reinvestment plan	277		277
Share-based Payment Arrangement, Noncash Expense	60		16					44
Stock Issued During Period, Value, Employee Stock Purchase Plan	138		37					101
Share-based Compensation	598		598
Balance, September 30, 2021 at Sep. 30, 2021	831,882		$ 685,428			$ 189,508	$ (5,888)	$ (37,166)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Acquisitions	$ 261,899			$ 261,899