Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Unallocated ESOP Shares	Accumulated Other Comprehensive Loss	Treasury Stock
Stockholders' equity, beginning balance at Dec. 31, 2018		$ 269,584	$ 19,035	$ 314,533	$ 29,257	$ (100)	$ (13,810)	$ (79,331)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		17,668			17,668
Other Comprehensive Income		4,163					4,163
Cash Dividends Paid	[1]	(7,528)			(7,528)
Stock Options Exercised, Net		1,325		638				687
Shares Issued Under the Directors' Stock		130		86				44
Shares Issued Under the Employee Stock Purchase Plan		250		163				87
Shares Issued for Dividend Reinvestment Plans		904		615				289
Stock-Based Compensation Expense		194		194
Purchases of Treasury Stock		(2,041)						(2,041)
Stockholders' equity, ending balance at Jun. 30, 2019		284,649	19,035	316,229	39,397	(100)	(9,647)	(80,265)
Stockholders' equity, beginning balance at Mar. 31, 2019		276,609	19,035	315,262	34,231	(100)	(11,567)	(80,252)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		8,934			8,934
Other Comprehensive Income		1,920					1,920
Cash Dividends Paid	[1]	(3,768)			(3,768)
Stock Options Exercised, Net		790		389				401
Shares Issued Under the Directors' Stock		130		86				44
Shares Issued Under the Employee Stock Purchase Plan		133		87				46
Shares Issued for Dividend Reinvestment Plans		451		306				145
Stock-Based Compensation Expense		99		99
Purchases of Treasury Stock		(649)						(649)
Stockholders' equity, ending balance at Jun. 30, 2019		284,649	19,035	316,229	39,397	(100)	(9,647)	(80,265)
Stockholders' equity, beginning balance at Dec. 31, 2019		301,728	19,606	335,355	33,218	0	(6,357)	(80,094)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		17,286			17,286
Other Comprehensive Income		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	0	(276)	(80,990)
Stockholders' equity, beginning balance at Mar. 31, 2020		309,398	19,606	336,021	37,441	0	(2,412)	(81,258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		9,159			9,159
Other Comprehensive Income		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	$ 0	$ (276)	$ (80,990)

[1] Cash dividends paid per share have been adjusted for the September 27, 2019 3% stock dividend.