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 Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2016		$ 232,852	$ 17,943	$ 270,880	$ 28,644	$ (400)	$ (6,834)	$ (77,381)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		29,326			29,326
Other Comprehensive Income (Loss)		(35)					(35)
Reclassification due to the adoption of ASU No. 2018-02		0			1,645		(1,645)
Stock Dividend		0	538	16,660	(17,198)
Cash Dividends Paid	[1]	(13,599)			(13,599)
Shares Issued for Stock Option Exercises, net		1,190		544				646
Shares Issued Under the Directors' Stock Plan		233		160				73
Shares Issued Under the Employee Stock Purchase Plan		496		331				165
Shares Issued for Dividend Reinvestment Plans		1,684		1,140				544
Stock-Based Compensation Expense		351		351
Purchases of Treasury Stock		(3,248)						(3,248)
Allocation of ESOP Stock		353		153		200
Ending balance at Dec. 31, 2017		249,603	18,481	290,219	28,818	(200)	(8,514)	(79,201)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		36,279			36,279
Other Comprehensive Income (Loss)		(4,965)					(4,965)
Stock Dividend	[2]	0	554	21,126	(21,680)
Cash Dividends Paid	[1]	(14,389)			(14,389)
Shares Issued for Stock Option Exercises, net		2,255		1,079				1,176
Shares Issued Under the Directors' Stock Plan		205		142				63
Shares Issued Under the Employee Stock Purchase Plan		505		340				165
Shares Issued for Dividend Reinvestment Plans		1,761		1,197				564
Stock-Based Compensation Expense		356		356
Purchases of Treasury Stock		(2,098)						(2,098)
Allocation of ESOP Stock		174		74		100
Ending 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		37,475			37,475
Other Comprehensive Income (Loss)		7,453					7,453
Stock Dividend	[2]	0	571	17,737	(18,308)
Cash Dividends Paid	[1]	(15,206)			(15,206)
Shares Issued for Stock Option Exercises, net		1,792		877				915
Shares Issued Under the Directors' Stock Plan		258		177				81
Shares Issued Under the Employee Stock Purchase Plan		493		328				165
Shares Issued for Dividend Reinvestment Plans		1,777		1,232				545
Stock-Based Compensation Expense		391		391
Purchases of Treasury Stock		(2,469)						(2,469)
Allocation of ESOP Stock		180		80		100
Ending balance at Dec. 31, 2019		$ 301,728	$ 19,606	$ 335,355	$ 33,218	$ 0	$ (6,357)	$ (80,094)

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

[2] Included in the shares issued for the 3% stock dividend in 2019 were treasury shares of 134,922 and unallocated ESOP shares of 150.