Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Common Stock	Common Stock Cumulative Effect, Period of Adoption, Adjusted Balance	Additional Paid-In Capital	Additional Paid-In Capital Cumulative Effect, Period of Adoption, Adjusted Balance	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings Cumulative Effect, Period of Adoption, Adjusted Balance	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Cumulative Effect, Period of Adoption, Adjusted Balance	Treasury Stock	Treasury Stock Cumulative Effect, Period of Adoption, Adjusted Balance
Stockholders' equity, beginning balance at Dec. 31, 2019	$ 301,728			$ 19,606		$ 335,355		$ 33,218			$ (6,357)		$ (80,094)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	17,286							17,286
Other Comprehensive Income (Loss)	6,081										6,081
Cash Dividends Paid	(7,800)							(7,800)
Stock Options Exercised, Net	408					237							171
Shares Issued Under the Directors' Stock	125					83							42
Shares Issued Under the Employee Stock Purchase Plan	265					176							89
Shares Issued for Dividend Reinvestment Plans	892					583							309
Stock-Based Compensation Expense	209					209
Purchases of Treasury Stock	(1,507)												(1,507)
Stockholders' equity, ending balance at Jun. 30, 2020	317,687			19,606		336,643		42,704			(276)		(80,990)
Stockholders' equity, beginning balance at Mar. 31, 2020	309,398			19,606		336,021		37,441			(2,412)		(81,258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	9,159							9,159
Other Comprehensive Income (Loss)	2,136										2,136
Cash Dividends Paid	(3,896)							(3,896)
Stock Options Exercised, Net	65					38							27
Shares Issued Under the Directors' Stock	125					83							42
Shares Issued Under the Employee Stock Purchase Plan	144					92							52
Shares Issued for Dividend Reinvestment Plans	450					303							147
Stock-Based Compensation Expense	106					106
Stockholders' equity, ending balance at Jun. 30, 2020	317,687			19,606		336,643		42,704			(276)		(80,990)
Stockholders' equity, beginning balance at Dec. 31, 2020	334,392	$ 120	$ 334,512	20,194	$ 20,194	353,662	$ 353,662	41,899	$ 120	$ 42,019	(816)	$ (816)	(80,547)	$ (80,547)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	26,559							26,559
Other Comprehensive Income (Loss)	(1,842)										(1,842)
Cash Dividends Paid	(8,084)							(8,084)
Stock Options Exercised, Net	525					326							199
Shares Issued Under the Directors' Stock	189					137							52
Shares Issued Under the Employee Stock Purchase Plan	246					175							71
Shares Issued for Dividend Reinvestment Plans	911					688							223
Stock-Based Compensation Expense	207					207
Purchases of Treasury Stock	(190)												(190)
Stockholders' equity, ending balance at Jun. 30, 2021	353,033			20,194		355,195		60,494			(2,658)		(80,192)
Stockholders' equity, beginning balance at Mar. 31, 2021	342,413			20,194		354,358		51,263			(3,096)		(80,306)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	13,279							13,279
Other Comprehensive Income (Loss)	438										438
Cash Dividends Paid	(4,048)							(4,048)
Stock Options Exercised, Net	369					232							137
Shares Issued Under the Directors' Stock	91					67							24
Shares Issued Under the Employee Stock Purchase Plan	122					89							33
Shares Issued for Dividend Reinvestment Plans	456					346							110
Stock-Based Compensation Expense	103					103
Purchases of Treasury Stock	(190)												(190)
Stockholders' equity, ending balance at Jun. 30, 2021	$ 353,033			$ 20,194		$ 355,195		$ 60,494			$ (2,658)		$ (80,192)